When you say you don't care to be at the start of the party, have you ever been to
MVMCP before? There is no way I would do an ADR at that time if I was going to the Christmas party. We have been to MVMCP every year for the last 5 years, and for the last 4 years we have gone to multiple parties each trip because DD is huge on the characters and there just isn't enough time in one party for us to see all the characters she wants to see (basically ALL the characters) and do everything else we want to do as well. You have paid a lot for those party tickets and you really don't want to give up party time. CP is notorious for not getting people seated on time. There is a possibility you could have a 20-30 minute wait to get a table. I also think that the TS restaurants at MK are generally pretty crowded on MVMCP night about that time because people not going to the party will make an ADR within 15 to 45 minutes before the park closes so as not to miss out on much park time and to maximize their day. I think this could lead to some table waits. You can expect a meal at CP to take approximately an hour and a half if you want to see all the characters at your table (you could get lucky and get seated right as they are getting to your area which could make it quicker). It could really cut into your party time.
Also if you are wanting to see some of the most popular party characters, you should know that the lines will start forming prior to the party and will stay long the entire party. For the most popular characters, I have been in line at 6:00 p.m. before, and on any MVMCP night, I am almost always in line for someone by 6:30. Two years ago, we got to Red Dress Belle at 7:05 because DD's top priority was the Cinderella crew, so I had gotten in line there before the party to hit them first. We went straight from there to Belle. By the time we got to Belle 5 minutes after the party started, her line was 2 hours long! We never saw it less than an hour and a half, so we didn't see her that night. Our 2nd party night that year, we made Belle the priority and I got in line at 6:15, and we were already about the 10th or 15th group in line. (Now, red dress Belle and Beast were removed from the party last year, so unless they re-appear this year that is a non-issue- but that is what you can expect from some of the really popular lines!)
On party nights we generally do a big TS lunch and then just grab some quick CS for dinner. If you are going to do a TS dinner on a party night, we would do one at 4:30 or no later than 5:00. That way, you should be out by 6 or 6:30.
