Each blister pack of Microgynon 21 contains 21 identical tablets, so it doesn't matter which one you start. However, for order and better control of taking the drug - please start with the first tablet in the blister. In this way - taking 1 tablet 3 times a day for 7 days - you will use the entire package at the prescribed time of therapy. As I have already mentioned - all Microgynon 21 tablets have the same composition: 30 micrograms ethinylestradiol and 150 micrograms levonorgestrel. On the packaging, each tablet is marked with the day of the week on which it should be taken - this information, however, is for patients who use the preparation in a standard way, i.e. one tablet a day to prevent pregnancy. I enclose additional information about Microgynon - prescription preparations can be reserved at GdziePoLek and collected stationary upon presentation of the prescription. Microgynon 21 is currently quite difficult to access: https://www.gdziepolek.pl/produkty/48863/microgynon-21-tabletki-powlekane/apteki/w-warszawie If you have additional questions about the use of this medicine, please ask your question in this thread.