I have been watching poly reservations for early december every few days or so for the last few months and right at about 6 weeks before the 7 month window, early december started booking up. I was surprised and hoping that wouldn't happen, but not really. There is a very small window of low crowds + christmas stuff - unlike other popular times like food and wine festival and the halloween party which run for months. That said I was surprised that thanksgiving, christmas, new years are all still available. I think there might be a nonzero chance of getting it just because I think that MOST people who plan for christmas/new years would likely plan in advance assuming it will be tough to get. If it is available at the 7 month window, I assume it will go in seconds... but still kind of surprised by how booked up everything is for the first week of december already while the major holidays stay available. I was also watching BLT for my backup to Poly and that is gone (all room sizes) for most days that week as well - it seems like as soon as the xmas party dates were released, the next day the xmas party nights at BLT were all gone.
it's all speculation of course but interesting to see what happens.