I would recomend starting at 3-4 years or so, it's more or less the age at which most of the people in my family started playing games, because first the kids need to learn somethings beforehand like basic shapes, colors, simple objects, animals, and do some physical games/activities to develop their motion and awareness skils, and then start with some of the letters and numbers, also before that age the kids need to sleep for long periods of time to develop correctly so exposing them to bright colorful screens for long periods of time isn't recommendable whether it be TV, phone screens, computer, the console etc because the lights can disrupt the perception of the body of the night/day and of the sleeping cycles, so you need to limit screentime, and when you start introducing them to play the games as others have said it's advisable to make it organically, you have to always be there to explain everything to them, to make sure they don't start throwing tantrums or getting excessively frustrated or angry if they aren't progressing in a game, and also you have explain that they can't be playing for hours and hours and that must be done during all the childhood and for the majority of their adolescence, at least that's how my family did it with me, my brothers, cousins etc, when my brother and her wife were working for extended periods of time I used to take care of my nephew when he was little and as others say it's good to start with games with simple mechanics like Space Invaders, Pac-man, Mario, Tetris, bubble bobble, etc. since the kid needs to make the association as to what is happening on the screen when he presses a button or gives somekind of input, while other modern games have "too much" going on the screen, Super Mario Bros. is always a good starting point since it covers a lot of the things that make a game entertaining and rewarding, but if you don't have access to it or to similar games, there are good games with simple mechanics for smartphones, games like angry birds, cut the rope, fruit ninja, and others with simple touch controls make it easy for the kids to learn the basic interactiveness of games and i must add that are also playable/winnable, then after the kids become proficient in playing the game it's good to make them establish the goals, for example it's true that you can't die in Kirby's Epic Yarn but if you get hit a lot and don't collect enough jewels you wouldn't unlock the next levels, also even when you unlock all levels there are tons of hidden collectibles in the game to 100% it, so you can tell the kids that is always good practice to "Finish all things they start".

To all the dudes saying that it would be better to make the kids learn other thing like reading, i don't see where videogames/electronic gaming is exclusionary with other activities or why it should become some kind of addiction, the problem comes when parents think that the TV, movies, videogames, and now smartphones or Netflix are some kind of electronic nanny that takes of your hands the responsabilities of taking care of and teaching your children, i started playing Super Mario Bros. at 3 year old, at that didn't hamper my developement in any way on the contrary it helped me and my brothers, and relatives to have better motion abilities, to have better spatial understanding, to have better reaction times, to be better at analyzing the functioning of things, to don't be like those people that aren't that old but still always say that "i don't know how to use that devices" "don't ask me anything i don't know how that thing works" and many other things. for example after we grew up a bit, after Mario and NES games, PC games like "lemmings" were great puzzles to make you think about how to spend your resources and timing your actions, also they had classical music on the levels, or some Electronic Arts about some kids that were detectives were very interesting, a kinda encyclopedia game called kaleidoscope that teached things about sciences made biology interesting, oh and the game Math rescue was a blast thanks to that game we got very good at arithmetic so making basic operations was never a hassle at school , i started to understand english thanks to, despite being a meme or not, the Mario is Missing PC CD deluxe game, and later by trying to translate the dialogs in Wing Commander and a story about imperium of man w40k in the manual of DOS game Space Hulk, we played a lot but there were still limits imposed by our parents, we were three so no one could monopolize the consoles or the PC more than two or three hours a day, that made gaming a important part of our developement but not something that overshadowed everything else, i still played regularly despite University being very busy and completed succesfuly my career in geophysics, or my brother he used to play the heck out of all Zeldas Majora's Mask being his favorite, now he is almost got his PhD in mathematics and buyed the switch to play Breath of the Wild, while his son now a bit older plays kirby, yokai watch and pokemon.

I can't speak for others, but now I feel the need to clarify, just in case I didn't made my point clear in my previous post (English is not my native language), that I never meant to say or imply that gaming is an exclusionary hobbie, or that it will become an addiction, or that it can't be educational. On the contrary: I 100% agree with you on all that. =) My one and only point was that gaming is going to happen with or without a push from the parents: the child already watches his father playing games, so it's just a matter of time that he also wants to do it. So in the eventually that the OP wants to introduce his son to a hobbie, I'd rather choose one that the child is less likely to develop naturally, without any external pushes. And the most obvious candidate is reading, because while other hobbies will more than probably be a part of his life when he grows up, reading may not be.

For instance, it's very likely that his future friends will suggest him to go to the movies or to play X sport, but no one's gonna tell him: "Hey! Why don't we go to the library, pick a book each one and spent the whole afternoon reading?" That just doesn't happen. And in school he will be introduced to a lot of activities, and reading will be indeed one of them, but in this particular context, reading will probably be the one that he enjoys the least, because it will be more time-demanding or less dynamic (or both) than all the others, so he will associate it with something annoying and boring.

And there are also other kinds of hobbies that I think shouldn't be introduced to anybody (they should just come out naturally), like playing a musical instrument, for example. I think it's perfectly fine that children are simply exposed to those activities (not actively introduced to them) and see if they like them or are good enough at them, but doing more than that would be kind of a forced situation, because those activities require (a lot) more dedication in order to be enjoyed to their fullest.

But anyway, my point is simply that reading is a hard-to-get-into and hard-to-digest activity if you're not accustomed to it in the first place, while other activities are way more accesible. It's not that gaming is somehow inherently worse or something - it's not.

That said, I do think that reading has an advantage that no other activity has, and that's the potential access to all the existing knowledge in the world. And I highlight the word 'potential' because there's obviously no material time for anyone to be able to access to such amount of knowledge (and people generally read fiction, rather than essays), but it's still something that no other activity in the whole world can offer, and that alone would be a very good reason to consider introducing someone to reading even when there were no other external factors in play (which is not to say that people who dislike, hate or are indifferent to reading don't have that access: they do - it's just that they're a lot less likely to make as much use of it as someone who actually likes books and enjoys reading).

But other than that, no activity is better or worst than any other; it's just a matter of which one fits better or worse with the tastes of each person. And as I said before: the more the merrier, in my opinion.

[Edit] In any case, this is nothing but a suggestion and whatever the OP decides is good. And I'm assuming all the time that he'll introduce his toddler to gaming anyway - I just wanted to put my two cents.

I can’t actually tell if this is a joke (sorry, maybe I’m too dull) but this struck me. A jock didn’t invent the wheel, a jock didn’t invent electricity and a jock didn’t invent the phone I’m typing on now. Yes, a timid personality and the “geek” label may be a point of contention, but you know what? A jock mostly ends up the same way as the geek but with one difference -  a cocky jock never really develops a mind as they rely on their physical prowess and looks. A geek cultivates their mind and that remains into older age. Btw, you may think I’m saying this as I’m an unfortunate geek with an axe to grind; this couldn’t be further from the truth. I am simply a man who loves video games and it is a huge passion but I love socialising, reading, travelling, working out and being a handsome b*****d who has sex with a lot of guys (I’m gay). 

So, the point being to the OP - if you have a passion you want to share with your son, do it. He may love it, he may not. But by sharing your passion and introducing him to a world that is so diverse and rich and full of art, he will lose nothing. He will be who he is regardless. You sound like a great dad, keep it up!