When you cycle is done..ammonia & nitrites would have dropped to zero and your nitrates would have risen..then you would do a water change to knock them back down..after that a small clean up crew can be added.
Be sure to feed the CUC as there really won't be anything much for them to 'clean up' yet and you have to make sure all of the new bacteria you just grew (the point of the cycle) has something to eat. A pinch of flakes every other day will do.