The tact that I'm taking is to schedule early. I schedule the interview within 1-2 days of receiving the invite. That way programs know that I'm interested and that I'm not just leaving them hanging. Think about it, by not scheduling an interview you're either indicating that you're taking your time in putting your schedule together or that you're probably not ever going to schedule the interview. How is a program going to know? They don't know! And they're probably going to start the next round of invitations and the days you were interested in may be gone.
There is absolutely no harm done in rescheduling an interview. These folks know that many of us will be criss-crossing the country and we need to keep things as efficient and economical as possible. I've already rescheduled one interview and the program coordinator was more than happy to accommodate. In fact, I explained why I was rescheduling and she said she completely understood. Rescheduling is a common practice--my friends from last year's class applying to IM, ortho, anesthesia, etc. all rescheduled once and sometimes twice and none felt like it was a mark against them.
If you don't take my word for it, read Iserson's. This is the approach he recommends. And I figure that he probably knows more than the average med student about interviewing.
