The check-in dates for last year were
Oct 1-6, 2011
Oct 22-Nov 3, 2011
Nov 12-17, 2011
Nov 26-Dec 1, 2011
Dec 10-Dec 17, 2011
Thanksgiving was November 24. This year it is November 22. You can see there were several blackout dates after December 1.
The Fantasyland expansion will open in stages. Part of Storybook Circus has already opened. Disney gives the following timetable for the rest of the expansion:
Late 2012 – Under the Sea ~ Journey of the Little Mermaid ride, Be Our Guest restaurant, Beauty and the Beast village, Belle meet-and-greet, Castle wall
Early 2013 – Remaining half of Storybook Circus with Pete’s Silly Sideshow
Late 2013 – Seven Dwarfs Mine Train roller coaster
As you can see they are not giving out any exact dates.