This depends upon your med school to some extent...i was required to take four rotations and left with four electives. I did two electives in July/Aug in areas related to my choosen specialty, then two others during the year (rads and gas). You can do them at your home location (if you are interested in staying there for residency or need to get some LORs) or rotate away if there is a certain program you really want to check out. I stayed at home, mainly because i needed LORs (which you can get away if you want), didn't have any specific program in mind to visit, and didn't want to spend the money (sort of lame, i know). You should also have some vacation time for interviews, which i scheduled in dec and jan. All this depends on what you are going in to. I would discuss these issues with an adviser in your specialty who knows you well. Best of luck.