Being on the wait list can be hard, but there certainly is hope!
I would say that it depends on the school to some extent. Some schools are pretty conservative with their acceptances and historically waitlist a lot of applicants and then pull from the waitlist in like January / February, while other schools accept a lot of applicants outright and then wait for a significant amount to withdraw around the May deadline. So I would recommend finding out what the movement at the schools you were waitlisted was like last year, and when it started.
Having said that, I don't think that sending a letter of interest now and another in the spring could hurt. Also, don't be afraid to let a school know that it is your number one choice (if it is).
