Hi Paige!
Your question is one we get quite often and it is a bit complicated to answer. It often depends on what kind of transportation you will be depending on. Will you have your own car or will you be using the complimentary bus, boat, and monorail? Are you also open to using a taxi or the Uber or Lyft service in the area?
Generally, Disney recommends all guests give themselves between an hour and a half to two hours to reach their dining destination. This is especially true if you will be taking the bus from the
All Star Music Resort. This resort is located closest to the Animal Kingdom Park but it is quite a trek to the other three parks. You must also bank on waiting 15-20 minutes for a bus. There are times when they get off sync and it can be an even longer wait. The worst feeling is standing there waiting and watching your time disappear to make a dining reservation. It is always better to have plenty of extra time then not enough.
If you plan on using your own car or a taxi and heading to another resort you can shave a bit of time off from what you would do for the parks. I would never leave less then 45 minutes ahead of time and honestly an hour is what I choose. After all, if you have extra time you can always head to the resort shop to see what they might have that you haven’t seen before. I haven’t shared that timing secret to my husband yet but I am sure he will catch on.
December can be a busy time depending on the date. So think about 2 hours for a park dining reservation and an hour for a resort reservation. If you are strictly using bus transportation for the resorts as well you will need at least two hours as you will have to head to a park and transfer to the next resort bus/boat/monorail.
You have some great reservations and I know you will enjoy each one!