How long do I have to apply the patch?

Once you reach your patch application day, the app will tell you in the "MyCycle" screen to apply the patch. Additionally, your patch application day will be highlighted in the calendar with a beige patch icon. Once you reach this day, you only have a total of two days to apply the patch. That is, the day the patch icon is displayed and the day after. 

After that, the app prevents you from activating the patch, otherwise the measurement period before ovulation would be too short. In order to detect the postovulatory temperature rise, the femSense algorithm needs comparison values. It collects these in the days before ovulation.