Early high school, pretty much universally because of Neopets. 17th of October, 2001, on what I can only assume is a criminally-insecure account (completely different username to what I go by, based on my old high school ID number). Thanks to Chrome for letting me dig that up!
It would be a while longer before I was inducted into any real Internet community. I played a bit of Counter-Strike throughout high school, I wasn't amazing, but I wasn't terrible. We had some pretty good players (who actually played online / vaguely competitively) over the years, but we rarely did anything more than LAN. Can't remember if that was firewall restrictions or not. My first real community came along in 2006, towards the end of high school. I'd gotten hooked on Dawn of War (for the uninitiated, a Warhammer 40k RTS) for a good while before that, and a good friend introduced me to an online community, with its own IRC server, forums and gaming nights. I couldn't do much
with that until university, because my parents strictly limited my computer time at home, and school was a continual balance between wrecking the IT systems and not getting suspended.
Funny, in hindsight. I was / am such a by-the-rules person, but I hated the restrictions people put on the IT systems at school. I went to a damn impressive school, and it had computer rooms for
days. Usage wasn't the problem, despite that being the general rule for "not messing about / playing games" - you'd potentially be depriving someone of a workstation. As someone who basically lived between the library and the IT rooms for the entirety of high school (
so cool 
), let me tell you. Apart from exam times, nobody was deprived of
anything.
My aptitude for computing only really came through this extracurricular messing about, and my time with Dawn of War lead me to take up games modding, before I even knew I wanted to do programming properly. Really made me the person I am today, hah. But that wasn't so much to do with the Internet exactly, as supposed to me not being allowed on it. Definite irony if any former teachers of mine come across this post (odds are one in a million, but still)
