My first game was Blue, and I got it not too long after the games originally came out in the US in '98...maybe like a week or two afterwards. I remember I kept checking the nearby store to see if they finally had it in... :P Ahh, I was happy to finally be able to get a copy of the game. I had really wanted to get it since reading about the games, and seeing the anime back then, had gotten me interested in them.
Blue, then Yellow, Gold, Silver, Red, and then Leaf Green, is the rough order in which I've gotten the gameboy games. I'd add in Fire Red as well, after Leaf Green, but...that's more my sister's game. I have all my old versions still (though I'm not sure where Red is at the moment), and they all still work, as far as I know.