Hi Apryl!
Thanks for stopping back by the Disney Parks Moms Panel with another great question. December is the most magical time of year to visit Walt Disney World Resort!
Mickey's Very Merry Christmas Party is one of my favorite special events and you are definitely in for a holly-jolly good time! If you want to be sure and get a good spot for the parade, I would plan to arrive at least an hour early and maybe even a little earlier just to be safe. I usually grab something for dinner and then have a curbside picnic while we wait. Main Street, U.S.A. is definitely busier before and after the parades, so you may want to find another spot to watch. You won't miss a thing if you choose to watch elsewhere except for the magical snowfall on Main Street, but you'll still have a chance to see it when you leave the park.
Be sure to take it easy earlier in the day and get some extra rest. That way you'll have plenty of energy to stay until the party is over. Guests are usually allowed to enter the park a couple of hours before the party officially begins, so you can take advantage of that extra time as well. Character greetings are always fun because they are dressed in their holiday attire which you normally don't see. So, I suggest taking some time to see your favorites and get a few pictures. And of course, eat lots of complimentary cookies and drink lots of cocoa!
I hope you have a wonderful holiday visit and you enjoy the party. Make lots of magical memories!
~Carrie