Hi Heather,
You magical Walt Disney World vacation is just around the corner. I am almost sure you are all giddy as you count down the days. Celebrating birthdays at this fabulous place will make those memories extra special. Be sure to ask for complimentary birthday buttons upon arrival. Special greetings from cast members and maybe even a few surprises await when the birthday girl/boy wears their button!
In regards to travel time, I always allow at least 45 minutes to an hour when traveling from my resort to a theme park dining reservation. This allows for time waiting on the
bus/boat/monorail, actual riding time, plus walking to the destination within the park. Since Be Our Guest Restaurant is toward the back of Magic Kingdom, it could take 10 minutes just to walk from the park entrance to the restaurant doors. Since your reservation is near park opening, keep in mind the queues to enter the park could also add on a few minutes.
When traveling between two resorts, I always recommend at least an hour since there is no direct transportation and a transfer will need to be made. In the case of 1900 Park Fare, you could take the bus to Magic Kingdom and then hop on the resort monorail to Disney's Grand Floridian Resort. Once on the monorail, you will be making several stops before you reach your destination, so that is why you will need that extra time. I am glad to hear that you chose 1900 Park Fare. It happens to be my absolute favorite character meal. I just know you will enjoy it.
I hope this helps you plan your days and transportation accordingly. Have a wonderful time! You will be heading to the magic before you can say "supercalifragilisticexpialidocious!"
~Allison L