IIRC, I joined when I was in like, grade 10, maybe?
I honestly barely remember anything at all from A0 now :/ Having a shitty memory sucks ass.
But anyway, I know I lurked there for a while, but I think it was maybe the summer of 2002 (or maybe 2003, I dunno) I joined.
My brother found the quasar 1.5x video on ebaums forums, showed it to me, and downloaded stepmania. Then I got into it and he said it sucked ass, and I began lurking on a few of those sites, like DDRUK, Bemanistyle, and later, a0.
I remember there was a bunch of shit with hayden getting banned and shit around the time I joined, IIRC.