Hello, Michael!
Personally, I don't recall Disney offering free dining during the month of December; these types of offers, instead, historically seem to fall during September and October.
I would suggest that you make your reservations for December when you can, but keep an eye on
Walt Disney World.com to see if anything different is offered for the time of your travel. While patterns are often repeated from year to year, changes do occur from time to time, so checking the site would be a good idea!
Regardless of all of that, December is a wonderful time of year to visit Walt Disney World! While the parks are usually so magical already, they are truly spectacular during the month of December. You are going to be so amazed by all of the holiday wonders you'll experience in December 2013!
Send more questions as you think of them; we'd love to help you plan the perfect holiday in Walt Disney World!