Hi Jann,
We're so glad you stopped by the Disney Parks Moms Panel with your question! You're going to have a fabulous time at the
Tomorrowland Terrace Fireworks Dessert Party! I can't think of a much sweeter ending to a day at Magic Kingdom than delicious desserts and front-row seats for Wishes Nighttime Spectacular.
I can understand your confusion with the reservation time, but hopefully I can help. For some dates, including those a couple months out or more, the reservation time defaults to 6:15 p.m. (or so). However, the celebration officially starts 1 hour before the start of Wishes and runs until the end of the fireworks. Right now, Wishes is scheduled to begin at 10:00 p.m. each night of your vacation, which means you should arrive by 9:00 p.m., but I'd recommend confirming that a couple weeks in advance and again on the day of your reservation just to be sure nothing has changed. You can do that by calling Disney Dining at (407) WDW-DINE (939-3463).
I hope that helps, Jann, and please write back if you have any other questions.
May all your wishes come true!
Beth