I think around an hour is a safe bet. We have generally had to wait around 10 minutes to be seated at LTT but since its a set menu and served family style, the food starts to arrive quickly. Characters arriving can be another story at any character meal. However if there is one you are waiting for and you're done with your meal, ask your server to hunt that character down. Also, make sure you arrive about 15 minutes early. If you arrive late, you will be seated late too and since you are paying for the party you don't want to miss any of it. I think you will come out just about perfect.