Hi Jennifer!
Although the scheduled dates for the Tomorrowland Terrace Fireworks Dessert Party appear to have been
set through until December 29th, reservations are usually only taken for the upcoming three months at a time. Currently reservations are indeed only being taken through until the end of September.
The great news is, since the upcoming schedule is already posted on the reservations page, it appears as though the party is happening
every evening during the week you're interested in, including November 20th. I've enjoyed the party with my family and friends many times now and it's a reservation I'd highly recommend!
I'd recommend that you try checking mid-August for bookings to open up into November, and if they still haven't then, I'd imagine that on September 1st they'll be very likely to open up through November.
Reserve your Tomorrowland Terrace Fireworks Dessert Party Online or by calling (407) WDW-DINE.
I welcome you to visit me again any time Jennifer and I'd be pleased to look into this further for you, or answer any other questions you might have!
Wishing you a simply Magical time at Walt Disney World and a spectacular evening watching Wishes at the Fireworks Dessert Party!
Kirsten