To find the first avatar just search your username in the VGC avatar catalogue and look for the lowest numbered file.
Um... mine sure isn't, but whatever.
This is my first one:
...Yeah, I know. Weird days, they were. Rocket didn't become a thing until about a week after I saw Guardians of the Galaxy (about 2 months after I joined), which was when I was beginning to accept that movie as my new favorite thing of all things, and stuff. Wasn't hyped at all for it pre-release, in fact I didn't care much for the MCU at the time, but I sure was hyped for "Zelda Wii U" (lol) and I think that awesome Nintendo presentation at E3 2014 was one of the main reasons I wanted to join the forum in the first place, so it makes sense that'd be my first avatar. But it is weird to think I had a different character there once (...let's pretend it was only once).