Hi Mallory, and welcome back to planDisney!
You are visiting
Walt Disney World Resort at one of the most magical times of the year! Each visit at that time of year puts me in the holiday spirit! Mickey’s Very Merry Christmas Party is a fun event, so you will not be disappointed.
Mickey’s Very Merry Christmas Party starts at 7:00 PM, and with a 6:15 dining reservation, you are free to keep your current reservation and enjoy your meal, and once you are done, you can exit the park. For many of our dining reservations, we usually show up earlier than our reserved time and (on occasion) have been accommodated, which was great. Based on some of my experiences, I would say as long as there is availability, there should be no issues with you being seated earlier. This is not guaranteed, but it doesn’t hurt to ask.
Please let us know if you have additional questions; we are here if you need us.
Have a magical time!
Raquel