If they are together he will do all the work when the time is right, the hens will typically squat on the ground when they are ready. He may be ready before they are but they will do as chickens will do..
He may seem that he is a bit rough with them in the beginning, but will calm down as he matures and with only one roo in the flock, he will not have to hurry to get done without another roo to come knock him off.