I would keep the carbon. Carbon is there to process anything the beneficial bacteria will not. Such as all the things we put in our tanks every day, from residue on hands, fish bags etc.
Also. I'd monitor my nitrates. Only you can know how often to do a water change. It depends on the size of the fish, the amount of food, and stocking levels. The only reason we do water changes is to A, remote nitrates, and B, removes built up metals, minerals etc.(this happens by topping off from evaporation.
I'd just monitor my nitrates, and do water changes as necessary. Meaning either nitrates go over 20-40, or water evaporation has happened.