Used at home colour this week to dye hair (darker). How long should I wait before highlights (salon)

Its normally best to wait for the colour to fade a bit before going for highlights. It sort of depends on how dark the colour is and how many times you have coloured your hair(how porous it is). The best advice I can give is to get a strand test with a small strip of your hair and see how it comes out, how light it goes and the condition of it after. Hope this helps.