Due to changes in my vacation time system it looks the only time we'll be able to travel this year is the 5 days between Christmas and New Year's. I started out really upset about canceling our Fall WDW trip but then found the Wyoming Winter Wonderland trip. My first choice will always be MNSSHP at MK but if that's my only shot at Disney magic this year I'll take it. 
With that in mind:
1) what's the latest I could/should wait to book?
and
2) are there any perks to booking through Disney (online or via phone) vs. booking with a travel agent?

With that in mind:
1) what's the latest I could/should wait to book?
and
2) are there any perks to booking through Disney (online or via phone) vs. booking with a travel agent?