When to apply for away rotations

I was wondering if those of you who have just gone through this could comment on when you submit applictions for away rotations. I was looking at UWisc and UMich for aways and both have visiting student applications as being submitted in May. Is this pretty typical of most away rotations? Anything you can do before then (besides having the application ready)?

Good luck to all of you who just submitted your rank lists!