Hi Nichole, It's always fun to hear from a fellow Bay-Stater!
Mickey's Very Merry Christmas Party is incredibly magical. You are going to be mesmerized by the Castle Dream Lights, the snow on Main Street, Holiday Wishes, cookies & hot cocoa and so much more...can I come with you too?? ;)
The Party officially starts at 7:00pm. I would make dinner reservations at 1900 Pare Fare for no later than 5:00pm. This will allow time for you to ride the monorail to the entrance and get there in time for 7.
Keep in mind that you are able gain early access to enter the Magic Kingdom at 4:00pm with your tickets if you'd like, so you may want to eat even earlier. If you do arrive early, be sure to head back to the front of Main Street around 7:00 or so. The experience of walking down Main Street towards the castle, while "snow" is falling around you...it's indescribable.
Hope this helps and have a Magical vacation,
Kaylene