6-9 months for a $60 dollar game. 1 day to 3 months if it's $30 or less.

No more than a year I'd say.

Anything more than that, and the hype becomes dormant until launch is super close, and speculation turns into degenerative rumors that 80% of the time lead to nowhere and become completely irrelevant by the time the game comes out.

Sooner is definitely better than later I feel, but I think no more than a year is good. If the game takes any longer the wait becomes annoying, and it if takes long enough, doubt will begin to set in, which I'm sure the companies involved don't want that at all.

The games should at least be 50% complete before being announced. Then come out within 6-12 months.

Who cares if the people say the series is dead.
It's not like that hurt fallout 4 sales in the slightest.

On topic, it should be announced a around 6 months before.
A lot of publishers are transitioning to a shorter turnaround.including Ubisoft Bethesda and Nintendo.

Sony and Square Enix have to step their game up on this matter.

Depends what the game is. Big games is nice to have time to build up hype for

But 6-12 months is generally good

A game should only appear at one E3 before it releases. I hate games that take up time at multiple E3s.

I think this is about right.  I also think it is incumbent upon pubs/devs to show at least some kind of in-game video or pictures at the time a game is announced.  

With that said, I don't mind announcements like "were busy working on the next Halo", or other things like this that just confirm things everybody already knows, no matter how far in advance.  But, situations like Death Stranding and Cyberpunk 2077, where they're "announcing" 4-5 years before release are really ridiculous.  

Most big games won't come out after 6-12 months if they're announced when they're 50% complete.

I guess it depends. I don’t mind a short (~3-6 months) turnaround from initial announcement to release. But I also don’t mind a little longer wait (~12-18 months).

I mean, aren’t people exited for games like God of War, Spider-Man, and Detroit even though it’s been 2-3 years since they were initially announced and that they were the big focus on Sony’s past two E3s?

Few games can handle long wait times. For example, Zelda Breath of the Wild had just less than four years between its initial E3 2014 reveal and it’s March 2017 release but has been given high praise, accolades, and is on track to be near the top of the best selling games in the franchise’s history. Others like Final Fantasy XV had a complete identity change for a long time and still took some time after to release. Yes the game had a favorable reception, but some could say it wasnt able to match up to the critical success of its predecessors like V, VI, VII, IX, or X.

Though some could also argue that big games that had a short span between initial announcement to launch needed more time. I don’t have examples on the top of my head but one could argue that the biggest pet peeve of this generation is that there are a pretty good amount of games that shouldn’t have released with so little content at full price or had made unfulfilling promises or decided to hold back on content to be released via microtransactions or DLC packs.