almostlegal- I would hold out as long as you can. You probably won't be getting a seat that opened up on June 1st, but if someone was holding a seat at your school and got accepted off a waitlist themselves it would take them a little while to decide where they wanted to go before they pulled out. If they wanted to get confirmation back from their new school before they pulled out it would take even longer for their seat to open up. It's less likely as time goes by, but it can still happen. I wouldn't give up just because they are taking a long time, but I would pull out when you absolutely need to make alternative plans.