i'm going on a cruise to Jamaica and the Cayman Islands so i'm gonna be getting a lot of sun and i want those natural high lights in my hair, but i want to dye my hair back to the color of my roots ((right now it's light auburn brown, and my natural hair color is medium brown))) should i dye it before or after i go on it considering i want my natural highlights in it, because if i dye it after it will just dye over it??