For the past three years, Jack and Sally have started meet and greets around 6:00 p.m. No guarantee they will come out early again this year, but I would look for reports from the first parties, unless you are going to the first party. We are usually in line by 4:30. We have never been at the front of the line, but haven't been horribly far back either. The line really starts building at 4:45. CMs will check to be sure everyone in line has a party wristband. If they come out early, you can be done seeing them before the party even starts. One year, on a non-sold out party day, we even got done early enough to go get in the 7 Dwarfs line after without a horrible wait.