Best to pick a UY that has you traveling only within your banking window. Sounds like you know that.
Pros: Dec UY seems to be one of the most easy to obtain via resale. Even if you're buying direct, most members find themselves with add-on-itis at some point and many choose resale for adding on.
Looks like you're not revolving aroung school breaks. So, if you don't have kids now, but may in the future, Dec means your banking window is open thru July and some families find it easier to travel in the summer when the kids are school age. (future flexibility)
Cons: You plan on traveling early Dec like the rest of the members (lol) and may find yourself needing to walk a room at some point in your life but you can't really start walking until Dec 1. Or if you're simply wanting to arrive on Nov 30th because of how the days fall on the calendar in a particular year, crossing UY's means 2 reservations, and leaving some points subject to a complete loss in the event of a need to cancel.
Don't know if the Cons are that big of a deal. I have an Oct UY and while I find it ideal because Thanksgiving is our most frequent visiting time, I find it a bit limited in terms of finding resale contracts for add-ons. Flip side.... if you need to sell, it's likely to go fast. So, since Oct is your next logical choice, consider yourself warned! lol