I would say the entire group should be formed fairly quickly - at least within the first six posts or so. There's going to be a lot of people out roaming around and people will naturally group together (power in numbers) and four's a good, solid choice - not so few that they can't, working together, handle a werewolf, but not so many they're extremely conspicuous, you know?

But your suggestion is just to jump right into it, eh? I'm down with that. I think I'll go ahead and start working on it now. Also, I do agree that everyone should either be from the royal city or one of the immediately surrounding cities, and group up en route to the last good direction that the princess was known to have gone.