Soojin's blog said that there will be calls made on May 15. I think some will be to R3 applicants and some will be to WLed folks. I am guessing there will only be a *few* of each since Michigan is retaining admitted candidates at a higher rate this year than last year according to the blog post.
My guess is that on May 15 Ross will also cut a large chunk of the WL loose to (mercifully) not keep WLed people waiting all summer when they have no chance at an offer. I am guessing a few WLed people will be retained to fill the odd spots that'll open up in June/July/August. That is my *guess*. I have the impression that the WL at Ross is very large...
As was said before...GL to us all!!