My mom allowed me to wear it when I went into Jr. High. I was 13. She also took me to Merle Norman to get a make-over and learn how to properly apply it, since I did not want to learn from her. Merle Norman will cake it on, so you will have to tell them not to be so heavy handed with it, if you take her to a make-up counter... Better yet, there are probably make-up tutorials on YouTube, that kids can watch these days to learn. Just make sure you watch the video first, so that you can make sure that it definitely is a make-up tutorial she is about to watch.
My parents were always willing to let me be creative with make-up and hairdo's as long as my grades stayed where they needed to be. I also think there can be psychological clues, to parents, on how their daughters view themselves, based on how they wear their makeup. I know that might sound weird.... but sometimes kids don't talk to their parents about what is really going on. You can tell a lot about your daughters if you pay attention to the way they present themselves, and then address issues from there.