If they're not going to let you know where you are on the waitlist, then you have no idea of when you're going to find out. If their deadline is May 1st for deposits, once they start finding out how many people are attending they'll start pulling from the waitlist. You could hear sometime in the summer, or not until the first day of classes. It's kind of a crapshoot. Have you sent in a LOCI, or any other extras yet?