However, I've read about a number of folks telling their guides that they'd like to buy in, and would do so "now" if they could be assured of a specific reservation...you might want to try that (if you're willing to buy "now," of course) w/your guide...just tell him/her that if you knew you could get an SSR studio 12/21-12/23, you'd put your deposit down right now...if not, well, you still need to keep thinking for a bit longer...
I've read that guides can sometimes make these kinds of "accommodations" happen...not sure it's true, but all it would cost is a phone call to find out...
Good luck!