Most people rotate through their home program and then do two aways. You ideally want to schedule them as early as possible. I think it's advantageous to start them in July and plow through them, so that you're done by October (you can do another ortho rotation then, if your school allows). You submit your application in September, and programs may start reviewing them shortly after that. Sometimes, letters take a while to come in, so if you're done with rotations by the beginning of October, you should have time to get your last letters in by the time programs start reviewing your stuff.
