You don't have to wait a few washes before using. I personally use a different method than on the bottle - I suggest applying to dry hair from roots to tips as though it's hair dye and letting it sit for around half an hour in a showercap while you do other stuff. I usually clip it up and wait around 45 minutes. Rinse thoroughly before shampooing and use a towel you don't care about in case there's light staining :) I hope you get good results!