You want the tank to be fully cycled before adding the discus. Honestly, keeping discus is much more difficult to do than cycling a tank, so you may want to take a step back.
You cannot cycle a tank without ammonia, whether it be from a fish, rotting food, or added directly (janitor's ammonia). I strongly recommend properly cycling with ammonia before getting your discus. You can add Nite-Out or another microbe/bacteria containing product to speed up the process. There is a lot of clear instructions out there on how to cycle with ammonia, and we are here to help!
Good luck!