Step 1 is enjoy 4th year--it's a more relaxed/fun year.
I found it helpful to do one of my SubI's (we had two required) late--I did mine in March. Quite a bit of 4th year rotations are electives, many of which are lighter, some of which are actually just "fluff" (radiology... they sent everyone home by 11 or so). You don't want to go from working 3-4hrs/day and having no responsibility whatsoever to internship. At least to me, that's a tough adjustment. So having a serious rotation in the months preceding July 1 can be helpful to kick you back into shape, so to speak.
With that said, you still need to take it with a grain of salt. My theory was I'd have a tough rotation right before internship. Instead, my attending (and head of IM at that particular VA hospital) kept saying "I'm so impressed you showed up after Match Day!" and typically sent me home by 3 or 4pm. I showed up around 7, and had a few patients of my own though, so it was certainly better prep for intern year than my radiology elective.
It's helpful to use your time off for Nov/Dec/Jan for interviews (your specialty may skew earlier or later). If you don't have enough time off, this is where you schedule those fluff electives/self-study electives. Typically they're the most accommodating to last minutes interview changes/offers.