My daughter (18) wanted to try it because I liked it so much. I'm not using it morning and night every single day as I use Retin-A (have been for 20 years) and don't want to get red and flaky. She is starting to have zits surface and I told her that happens a lot of the time when using a good product because it's bringing out all of the impurities. She's having a fit now (like 18 year olds do) because she has an event coming up this weekend. How long will it last??? Should she stop using it? Or what will help, FAST?