I do it nearly every time -- book at 11, change at 7. It gives me peace of mind to know, no matter what, we're going -- it's just a matter of where we'll hang our hats at the end of the day!
And besides, it gives me a reason to call MS again...for some reason, calling them just sets me in that "I'm gonna go on vacation!" mood, even if it is 11 mos away!