As noted, you cannot possibly use Dec 2021 points for a Nov 2020 trip. Moreover, you cannot now use those 20 Dec 2019 points for a Nov 2020 trip because you have banked them into Dec 2020 use year and they cannot be returned to the Dec 2019 use year. The only points you can use for that Nov 2020 trip are Dec 2020 points by borrowing them into the Dec 2019 use year.
As far as actually making a reservation, you can always book your home resort at 11 months out from arrival date. For example, you could book that Nov 2020 trip right now on Dec 26, 2019, and borrow the Dec 2020 points to do it, if the time you want to arrive in Nov 2020 is Nov 26 or earlier.
Note, I am assuming you do not mean that what you actually did was bank points from your Dec 2018 use year into your Dec 2019 use year so that both sets could be used in Nov 2020, and actually want to borrow Dec 2020 points. If that were the case you could use all three sets of points and make the Nov reservation right now if arrival date is on or before Nov 26, 2020.