From a waitlist veteran who got in....
Hang in there, guys. It's REALLY early yet. The May 15 deadline is actually kind of soft. I knew people who were still waiting to hear about financial aid awards, who simply could not decide between acceptances until they knew which school was going to give them more FA. Admissions Offices gave them leeway for that; obviously if that school's FA office was the one holding up the works, the admissions folks couldn't very well ditch someone while they tried to figure out their financial picture.
I also think the numbers are REALLY in your favor this year. You know that the overall number of candidates went down this year. That's a trend that's gone on for the past few years now. However, schools have established a "formula" of # of acceptances to offer vs. # of slots in a class, and I am willing to bet you that they haven't changed their formulas even with lower #s of applications. To me, it just seems logical that there will be more people pulled off waitlists this year.
My advice to all of you is to TRY and figure that you won't hear from anyone until June. That way if you get the call sooner you'll be pleasantly surprised!
Oh, and someone mentioned a 24-hour rule: this may vary by schools, I don't know, but it doesn't sound very practical or likely. Schools know that you all are in this position, and they are not going to be unreasonable in what they expect of you. I recommend honesty: when you get the call, TELL THEM that you've got other waitlist spots and ask them what is their policy regarding a commitment date. For me, it was easy - the $3K deposit for GWU was non-refundable after July 1 so when I hadn't gotten off another waitlist by then, that sealed the deal.
Rx for waitlist anxiety: 12 oz. cold beer, repeat prn. 😀