I'm using tretinoin at night and bp + aha during the day i want to add bha on my regimen.. is it ok? what the best time to use bha on my regimen?

Fine tune regimen: Tretinoin should only be used at night because of hypersensitivity to light caused by retin a (tretinoin). Bha is better than aha for acne since salicylic acid is lipophilic so it will work better than aha, don't use both. Since you are using the retin a (tretinoin), i would say to use bha in am. BP apply up to twice daily over affected areas. You may want to consider birth control if your acne is difficult to treat.