Cinderella's Royal Table is one of the most popular dining experiences at WDW. This, combined with the fact that the restaurant is fairly small, makes this a challenging reservation to come by. However, you are in a better position than you thought as far as trying to get into CRT. WDW recently changed its dining reservation booking window from 180 to 90 days. (Read more about this
HERE.) So the first opportunity that you would have to make reservations for Cinderella's Royal table is in mid-March.
I would call Disney Dining at 407-WDW-DINE in early March and ask them to confirm for you the EXACT date that you can call for reservations.
Beyond that, you have the best shot of getting reservations if you are on the phone at the EXACT moment that the phone lines open for the day. This strategy is described in great detail in the
Unofficial Guide to Walt Disney World -- a must-purchase for any Disney traveler, but
especially for one trying to reserve Cinderella's Royal Table. The Unofficial Guide includes 4 full
page of teeny type tips of how to get a reservation! Of course there are no guarantees, but most of the time when I follow the Unofficial Guide suggestions for getting a CRT reservation, I am successful.
Good luck!