Hi there Meredith!
Unfortunately, the information for next year's Mickey's Very Merry Christmas Party will not be released until about the beginning of the second quarter of next year. If you look at the dates for this year, the party typically runs around the same time frame, year to year. Here are this year's dates just as a quick reference;
November 8, 9, 11, 13, 15, 18, 27, 29, 30
December 2, 4, 6, 7, 9, 11, 13, 14, 16, 18
Keep a close eye on the Disney Parks Blog next Spring for the dates to the party! I hope this information helps you with your planning and if you have more questions, please ask away, we are always here to help! Have a Magical Time at the Walt Disney World Resort! Thanks so much for asking the Moms Panel!