My brother........ (plzz read)?

My brother is using this acne medication called Differin. How long do you have to wait until the medication actually works? He is using that one at night, and in the morning he uses two creams: Benzoyl Peroxide 5% gel, first, and second, Clindamycin Phosphate. Are all these 3 good combinations? These 3 were prescribed by his dermatologist. But the differin one he have been using for about 6 months, and the two in the morning he used for about 2 1/2 months. It showed some results. Please I REALLY NEED ANSWERS!