Will I pass a hair follicle test tomorrow

Hope for the best(?), plan for the worse! No REALLY plan for the worse! Would this be your first fail? You haven't given a lot of info but hair follicles tests detect drug use typically for the last 90 days.

21 months is a really impressive path to recovery. I know it isn't easy. A single use, 7 days ago is not likely to show positive on a hair test, from everything I have read. Keep working on staying clean! Don't let a slip become a relapse.