Hello Roberto! Welcome to the Disney Parks Moms Panel.
I am in a similar predicament in trying to obtain
Advanced Dining Reservations at Be Our Guest for my family's Walt Disney World Resort vacation this August.
When I cannot book certain Advanced Dining Reservations, I
check the date and times daily on the Be Our Guest Restaurant Reservations page and hope that someone else has changed their plans. It happens quite frequently and usually something opens up if you are flexible with times.
If you choose to "walk-up" for a reservation at Be Our Guest Restaurant, a Cast Member will do all they can to accommodate your request, however you could be looking at a lengthy wait time or be hoping for others to "no-show" their Advanced Dining Reservations. Cast Members cannot guarantee a "Walk-up" reservation may be fulfilled but if you are willing to wait, you may get lucky.
Be sure to check for Advanced Dining Reservations right up until you hope to dine as Guests frequently will cancel their reservations very late to avoid the "no-show" fee for not fulfilling their reservations.
If you are looking for a little more certainty for a wonderful sit-down dining experience at Magic Kingdom other than Be Our Guest, I recommend the
Jungle Navigation Co. Ltd. Skipper Canteen in Adventureland(especially if you are a fan of the Jungle Cruise attraction) or a
Buffet With Character at The Crystal Palace to meet Winnie the Pooh and all your favorite friends from the Hundred-Acre Wood.
Bon Appétit!
~Todd