You would be able to use the code for the days up through 11/24, but I'm not 100% sure you can use it for Thanksgiving day. Some people have said they were able to book their code for the duration of the trip (i.e. right now, if you booked a general public free dining trip to start on Oct. 3rd, the last day of availability, you can use the free dining for the duration of your trip).
It depends on what type of discount it is. If it is a room % discount, for example 40% off, you can only get it through 11/24. If it is for free dining, and you check in during the dates the code is valid, you will get it for your whole stay, even for the dates that fall outside the code. HTH.