I'd still add some ammonia source, even if just some flakes. Some may say its not necessary, but if you're cycled it won't hurt a thing. Just simulating the fish that are gonna go in there anyhow, so if they take the ammonia from the flakes, it'll be ready for the ammonia from the fish. Piece of mind starting up a new tank is always good, especially since you don't plan on adding fish right away anyhow.