I like to wash my hair 24-48 hours before I dye it. I don't add any products to it, and I've always gotten the best results that way. The color seems to take better without any buildup. I never wash less than 24 hours before because I don't want my scalp to burn. However, if I'm bleaching, I won't do it any sooner than 5 days after a wash because I don't want my scalp to be irritated at all. The chemicals in lighteners are pretty strong, so I want to give my scalp time to heal after being agitated by the scrubbing and the shampoo.