First seating is at 8:05. You would want to be at the park fairly early so you can be one of the first ones back to the castle. Things really get bottled up in the lobby taking pics with Cinderella sometimes.
It can be done though, and I would like to do this on our next trip too. Just be sure to let the server know that's what you have in mind so they are sure to get your ticket quickly.
Enjoy! Better to rush and enjoy, than to spend 45 minutes waiting in the lobby for pictures prior to seating like we did last year!