I think you should let the narrator have the option to open the story for applications further into the game. This could introduce the idea that not all the cast are introduced at the same time, and new important characters (controlled by new players) can join the action at a later date. It might mean that certain stories that you follow which you really like might open applications at a later date; imagine the excitement of getting to join one of your favourite films or TV shows, it would be like that!