Either/or, my body is ready, my soul prepared. Let's do this.
Serious Answer: The weekend of the 20th seems a bit too soon, when they're still struggling to get everyone's pre-purchases sorted out. I think it will land on the weekend of the 27th, or they may just push it back to May if there continues to be problem.
Yeah, you pay in full now, and then they open up the game for specific weekends. You'll be notified far in advance, so I wouldn't call it a 'strict schedule'. They've also said that it won't be 6 months, they know people want the game and they're using these Beta Events to test, not just generate word-of-mouth like every other MMO.
Still, your call; we'll look forward to seeing you when the game goes live. Check back here for news though.
Sounds kinda legit, though the open betas are supposed to be NDA-free.... hmm, I wonder if they're doing another Press Beta?