For seniors who’ve been placed on waitlists, the earliest you’re likely to hear any news is around May 8-10. After the May 1 deadline for admitted applicants to commit, colleges will count their enrollments through the first week of May and get a sense of whether or not they’re likely to fill the class. If it looks like they’re going to come up short, that’s when they’ll go to the waitlist. This is why even a good-hearted admissions officer can’t give you much sense of your waitlist status before then. They might need to take a couple hundred off the list; they might not need to take any. Some schools will wait until the end of June to review the final senior grades as part of this decision.
So that means two things for waitlisted students: Make absolutely sure you send in your deposit to another college that accepted you by May 1—don’t wait until you hear your waitlist status to commit to another school. And keep your senior grades up.
Thanks to Arun for his insight on this.