For the 3 parties I've been to, I ate at MK twice and BOTH times they had us wait right in front of the restaurant. I've eaten at both CP and LTT. LTT is right across from a photo booth so while we were waiting for 7:00p we got in the photo line (they wouldn't take any photos till right at 7:00p).
I was always done by 6:30p - 6:45p so maybe if you are done much earlier and were done by lets say 6:00p or earlier then they might usher you to either Fantasyland or Tomorrowland, the 2 places they sent people to who were attending the party and already in the park, but not eating in a restaurant.