Personally I did not start anywhere near day one.
However the questions have come up about the start date. And I found that to be a statistical data I figured I would learn it. So the mathematician/historian in me spent many hours finding the data and proof of the data when asked for.
The start date to w1: June 23rd, 2006
Beta was obviously before that, and the pnp would have been made either before beta or during the beta round. I am not sure how long beta ran as the only surviving data is that on which members that actually played it would know since all forums have been cleaned of it.
I do hope that when w1 is finally closed that it is kept at least viewable for everyone rather then all the history being cleared out of here.
Up until at least July 14th, 2006 they were still allowing members access to the pnp soli by hand checking each account to make sure it had an in game match.
w2 started exactly a month after w1 on: July 23rd, 2006