When you purchase this product for the first time, your Beauty Adviser should take the time to chart your darkest discoloration on two charts, one for you to take home and one for her to keep on your file. It will be dated with the date you purchased and plan on starting the treatment. If you use the product as directed, which is twice daily and you MUST wear a sunscreen as well, you will notice a small difference in the color in as little as 2 weeks. It will not be a significant change, but having the chart, you will be able to notice the small difference, which is also why the Beauty Adviser should book you back in for a 2 week appointment to follow up with you. To see a pretty drastic change, it typically takes 3 of the 1 oz. bottles, or 3 months. It is a commitment and sunscreen is a must in order to protect from further damage.