In general, it seems that the summer time is the easiest to book. Especially if you have any date flexibility. Give it a try, but have some alternatives lined up when you call.
Agree with disneynutz and Granny: you won't know until you call MS. In my experience, getting a 1BR at VWL in the summer has worked, even at such a late date. Have a second and third option lined up so that you know you'll have a room somewhere, then go on a waitlist for VWL. With all the weather issues regarding this winter, I like your odds of a waitlist coming through.