I think it's been at step 3 for longer than most sites have last. I know I'm part of group 2, but I've seen a somewhat consistent culture since I arrived over five years ago.
Before what date do you think people can be group #1? Or are you ascribing the group number to contributions rather than date of joining?
So after a few months of lurking, I registered here, and now it's my daily[1] go-to site.
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[1] Hourly. :)