I had a semi permanent color put into my hair about 2 weeks ago and it didn't seem to take. My hair is Sandy brown and I want to get blonde highlights, how long do I need to wait before applying the highlights?

This is difficult to answer based on the info provided. What is your natural hair color? What shade of semi permanent color did you use? When you say it "didn't take" does that mean you have grey hairs showing or do you mean there was no change at all to your color? Are you trying to use semi permanent color to lighten your hair and create highlights? (that will not work, since demi permanent does not "lift"). Please post some more info and then hopefully someone can help. :)