Need help with Game Center Match Making

I have an existing iPhone app (simple card game) in the app store and have been working the past few months to convert it to multiplayer. I am almost ready to release it for beta testing, but I am still not happy with my match making code. The game is set up to be 2-4 players. Unfortunately, the way my code currently works, as soon as 2 players join all match making activities stop and the game starts. I would like to be able to delay the game from starting to give the 3rd and 4th players time to join. I just need some sample code that shows how to first start a match, and then automatically implements [[GKMatchmaker sharedMatchmaker] addPlayersToMatch: for a certain amount of time. Thank you, MaroonE