I do them overnight before shampooing to nourish my hair and keep it from being stripped. Technically, I'm usually too lazy to warm the oil up so it's more like an oil treatment/prepoo. I shampoo every four days so I do them twice a week. It's convenient because I can't stand oil or anything heavy in my hair so doing them before shampooing allows me to have nourished but clean hair. I have been using red palm oil but I may be switching to coconut oil soon. Red palm oil stains everything and is a pain to wash out.