Hello again, Mysha,
For your arrival day, there is nothing more magical than visiting Magic Kingdom, taking in the ambiance, sights and sounds of Main Street, U.S.A. and viewing Cinderella Castle for the very first time. I'd suggest skipping an Advanced Dining Reservation for your first evening, as you many not want the commitment of having to sit in a restaurant for a long period of time. Magic Kingdom offers many quick-service dining locations, and Casey's Corner on Main Street is a family favorite for us!
Sofia the First is not currently entertaining diners at Hollywood & Vine, but can be found alongside Doc McStuffins and other friends in a brand new production at Disney Junior - Live on Stage! Picking up a Times Guide at the front of the Park will offer show times throughout the day, and keeping a watchful eye on the Disney Parks Blog will likely keep you in the loop of any changes to Character Dining.
With a little Tinker Bell fan, I would definitely suggest booking the
Tomorrowland Terrace Fireworks Dessert Party. Although subject to weather conditions, Tinker Bell will fly right overhead, and with an unobstructed view of Wishes nighttime spectacular and scrumptious desserts to enjoy, you're sure to have a magical time.
If there's any other advice I can offer, please feel free to visit me again.
Wishing you a wonderful vacation, Mysha!