My original was Yellow, which released on October 1, 1999, I got it that Christmas, so I was 4. I could read early on, so once my sister was done, (it was actually for her, but she got bored by New Year's) she gave it to me. I wouldn't have gotten the core mechanics were it not for the anime, which my sister had watched since it debuted. My sister gave me her Blue at Christmas 2000, because she had caught 'em all. My dad got me a Red version that same Christmas, so I had finished catching by the time G/S/C released. It was cool.
Come to think of it, I could've started earlier, because I read the first Harry Potter at 3 1/2.