It's important to follow the instructions provided by ZO® for the application of their products. In this case, you should apply the product to clean, dry skin at night as the last step in your skincare regimen. If you have any questions or concerns about the recommended order to apply your ZO® products or need further information, it's best to reach out to your local physician or use the live chat option to speak to a ZO® Skincare Specialist. They can provide you with personalized guidance and address any specific questions you may have about your skincare routine.