Just a general request from many of your fellow applicants who are on official waitlists or unofficial "we sent out interviews & rejections but didn't notify you, and if enough people cancel, we'll invite you" waitlists:
If you are able to swap interview dates, that's great. Scheduling these interviews & travel to them could legitimately employ a personal assistant for a lot of us. If, however, the interview date is rapidly approaching, and you have two interviews scheduled for that date, which is why I assume most of us are looking to swap dates, please go ahead and cancel one of the interviews. I have heard firsthand from a program coordinator that if they have cancellations within two weeks or within a week, they will not contact additional people to fill the slots in order not to "burden the applicants." I, personally, think we're all adults & we should be able to make our own decisions on paying for a flight or not. Also, this policy obviously does not apply to all programs.
Additionally, a previous poster mentioned cancellations within two weeks reflecting poorly on all future applicants from your program.
Just a few things to keep in mind when contemplating which interview you're going to on January 5th, 12th, 19th, etc.
Good luck to everyone & see you around the interview trail!