The skin is a living organ that takes approximately 6 weeks to adapt to a new skin care routine, so you should always use a new series / new product for a minimum of 6 weeks. The clinical studies carried out on our products have lasted over 8 weeks to show the long-term effects. How quickly or how much effect is experienced is very individual, and depends on your starting point. Degree of hydration, hormonal status, age, season, local factors on the skin, which products have been used before, exposure to sun, wind and weather are some of the factors that affect how much effect is achieved. That is some will experience a lot of improvement and others less. We have no guarantee that everyone will achieve the desired effect.