I think it's way towards the beginning, during the long intro with Roxas. There's a brief flashback scene (I don't remember exactly when during the intro it was) about Roxas fleeing from the Organization. There's a shot of a throne room with 13 thrones, and all of the Org. members sitting on them. The ones that we haven't met yet have their hoods up, but the CoM ones you can see: Vexen, Lexaeus, Zexion, Axel, Marluxia and Larxene sitting on their thrones.