How to estimate the pacing of a banquet luncheon?

We are having a banquet luncheon at a Chinese restaurant. Lunch will be served at around noon. We will have a DJ for dancing/games during lunch and dessert. I'm trying to figure out what time to tell people the event will end so they can pick up their kids. How do I figure out how long each course will take? There will be salad course, soup course, entree, dessert.