OK, your specialist can guide you when he or she performs the procedure. Why ? Because how long your skin takes to heal up after microneedling will depend on many factors including- the passes, the depth of needles, if energy such as RF was used, if the needles are insulated or not, the technique that was used (e.g.. step or layers), your skin sensitivities, the device itself, and many other factors. The use of PRP can improve healing times and results. Bottom line, it will vary, but skin is usually back to normal after 6 days, so 7 to 9 days will be fine. Obviously start at a lower concentration ie. mix moisturiser with retinol. As a passing comment, the use of glycolic acid after microneedling is not a good idea, this can result in PIH or post inflammatory hyper pigmentation or skin darkening, esp. in your skin type. Please follow the instructions of your specialist, and your skin will heal up in the quickest possible time, wishing you well. Dr Davin Lim. Brisbane. Australia.