Hi there Kerri,
I believe advanced planning is the key to successful Disney World vacation planning, so "kudos" to you for being on the ball!
Since you are planning to arrive in 2013, you unfortunately won't be able to purchase your Mickey's Not So Scary Halloween Party tickets until next Spring when they are released. Tickets for 2012's party dates just went on sale this week and based on historical trend, tickets for 2013's parties will most likely go on sale during this time next year.
If I've misinterpreted your arrival date, I apologize. Just in case you're wondering about THIS year's Mickey's Not So Scary Halloween Party, tickets for 2012 dates are on sale now and can be purchased ONLINE by visiting the official
Mickey's Not So Scary Halloween Party ticketing site.
If your trip is indeed in 2013, sorry I don't have better news. Believe me, this next year will fly by and you'll be headed to the Happiest Place on Earth before ya know it!
BOO To You and Hallowishes,
Amanda F.