Need help

I'm 5 weeks pregnant today and don't want to tell even family until 12 weeks. However my mother is a hair dresser and is insisting I need my hair colored soon, she says since I'm her daughter, it's making her look bad as a hair dresser, she's about half joking, but half serious when she says that. I really don't feel comfortable getting my hair colored, especially during the 1st trimester. She's very persistent and has already penciled me down for a day pretty much without my permission. I really don't want her to know I'm pregnant though till 12 weeks. Any advice on avoiding it until I can tell her? My mother and I pretty much have the same relationship as Lorelai and Emily on Gilmore Girls.