Hi, Anissa!
A spur of the moment trip to Walt Disney World is sometimes the best kind! You've picked a great time to do it, too, as crowds are typically lighter in mid- to late-January; as such, there may be more Advanced Dining Reservations available than you may think.
I went to
Disney's online Dining Reservation site and searched for reservations for dinner, party of 2, on January 13th, 2014 and found 87 results! While
some of the most popular times or locations may be booked, not all of them are! I suggest that you go ahead and make your Advanced Dining Reservations now, because while there may some great walk-in reservations available during your stay, why take the chance if you don't need to do so?
Go ahead and book that fantastic
Disney Dining Plan, Anissa, but keep in mind that you can book your ADRs as soon as you are ready, even if you haven't yet booked the Disney Dining Plan.
Happy planning!
Send more questions as you think of them, too. We love to help!