This is really last minute but I have an appointment tomorrow to get some highlights (it's part of a gift certificate with a bunch of different services on it). I'd really like my hair to be darker before I get the highlights but I can't afford to have it done at the salon so I was just going to do it at home tonight.
Will it ruin my hair if I dye it tonight and then go get a few highlights tomorrow? I know people do much crazier things with their hair but I am a pensive hair dyer so I just want to ask before I go and do it.
I would go for it. Making your hair darker than it is currently isn't as damaging as going lighter.
Or, instead of highlights, you could ask for lowlights. It wouldn't cost any more and would give a darkening effect you your hair, making the current color more like the highlights....