Hi Chrissy,
I expect that the 2012 dates for
Mickey's Not So Scary Halloween Party will be released within the next few weeks, probably during March. Follow the
Disney Parks Blog closely as they will be among the first to announce that tickets for this event have been released.
If you look at the 2011 dates, you'll notice that the party was almost always offered on Friday nights. I think it's a good bet that the party will be offered on the Friday during your trip. That might help you lay out your dining plans, tentatively, until the official 2012 dates are announced.
Remember that this party is a hard ticket event, meaning you will need to purchase a ticket specifically for the evening you plan to attend. Don't wait to purchase your tickets as some dates for this party do sell out.
Wishing you wonderful fun at Mickey's Not So Scary Halloween Party this fall!
Jill