The release dates of all the games are definitely important. I think that my hex edit of the GT2 demo disc was also a watershed moment -- people poured into the GTF back then because the FAQ was an exclusive source of GT2 pre-release information. I remember getting an official credit in Germany's Official Playstation Magazine, and became friends with Jaz, an editor over at IGN. The US producer of GT thought I ran GT.com, and we stay in touch to this day - though we haven't had the pleasure of meeting in person yet.
Bryan's GT Academy win is worthy of being on the timeline, too. And don't forget the GT party dates. We had at least four HTX-GTPs in Houston.