How quickly do clean & clear acne products work?

Maybe a week. This is salicylic acid for spot treatment. If you need to get rid of your acne for the prom within a week or two, get with your personal physician now -- a topical agent plus an antibiotic might do the trick. If you're on your own, you may get better overall results more cheaply applying topical benzoyl peroxide to all areas that have acne, as much as you can tolerate.