Hey ... so I did three away rotations (and one home sub-I) and it was totally fine. That said I did things a bit differently from other people. I did my home sub-I in March. They were hurting for help (cause I was the only med student on the service who was into ortho) so they were stoked to have me and it left me time in the fall to do my aways.
Additionally, I think you need a break between rotations. I had at least a week off between places. It meant that I never burned out, which can definitely happen if you are working like a dog (which you should be).
Lastly, I think early November should be that latest you do a rotation. People may disagree with me. But I think it's rude to be leaving a rotation to go on interviews if you're into that program and they may have sent out all their interview offers before you get there if you're rotating in December. Plus, interviews are stressful and I wouldn't want the added stress of doing an away at the same time.
So do what you want, just be smart about it. I think I was at my best around October. So I scheduled my most ambitious rotation then (and got a LOR out of it). July is chaos because of all the new interns... so it can be very hit or miss then, cause if you can help you're a stud but there may be fewer learning opportunities too.
Good luck and feel free to PM me if you have more questions.