Your fourth year is broken up into four-week blocks (equating to roughly one month each). At least two of the “early” rotations (up until around September/October) should probably be related to your chosen specialty (if you have one), since you’ll want at least two letters of recommendation from faculty members in your specialty. Since all applications are electronic, as soon as ERAS opens (first part of July), it’s a good idea to get your personal information in there (personal statement, address information, the basics so to speak). The ERAS post office opens on September 1 for the Dean’s Office to upload your letters of recommendation and picture. That is the day that residency programs can begin downloading your application as well. To download your application, programs do not necessarily need to have your Dean’s Letter or all your letters of recommendation (they simply assume that if you list those items on your application they will eventually get them). Therefore, many programs will invite you to interviews sin Dean’s Letter and/or full complement of letters of recommendation. All this means is that it behooves you to fill out your application early (to the best of your ability) and, once complete, with or without letters and Dean’s Letter, submit it.
Most students take December or January off for interviews, though the interview season typically begins in mid-November and can last into February. You’ll probably want to take one of those two months off and schedule an easy month for the other. Some of the most interview-friendly rotations are probably Primary Care, Radiology, or Anatomy Teaching Assistant. Keep in mind that many competitive specialties may only have a handful of interview dates to choose from, and you will likely not know what those dates are until you are invited. Do what you want during your fourth year. I think most would consider 4th year to be “front-loaded”: rotations where you want to impress letter writers, apply to programs, do interviews, travel, etc., encompasses the beginning of the year. After this is complete, things (typically) slow down a bit and you have more time to do what you want to do and make the most out of your 4th year experience.
Do the things that you are not going to do when you leave and go into your chosen specialty. Going abroad (Dr. Vermund’s office is a wonderful resource for opportunities abroad), working at other medical centers, and doing interesting and “hard” rotations in areas that you may never see again is good. Also, schedule some “me” time, enjoy sitting around with friends, and generally, have a good time. Once intern year starts, you are going to have to pay the piper regardless of what you did during your fourth year. After you do your “audition” rotation(s), do all your rotations in fields complimentary to your field of career choice, minimizing overlap. This year may be the only chance you have for the rest of your life to take a month and really concentrate on dermatology, interventional radiology, ophthalmology, etc.—areas of medical knowledge that are notorious for being inadequate amongst most physicians not dedicated to those fields.