Hi Caroline. Professor Studd is quite unusual in prescribing Utrogestan for such a short period as this can be more risky in terms of thickened endometrial lining. I think he does this so that women can avoid the symptoms of progesterone intolerance. The standard recommendation is that progesterone be taken for 12-14 days a month. This is to ensure that you have a proper bleed and all the endometrial lining is shed. If you take Utrogestan for only 7 days a month you will need to be closely monitored for thickening of your endometrial lining by having more frequent vaginal ultrasounds. Professor Studd usually advises women to start taking Utrogestan on the 1st day of the calendar month as this is the simplest procedure, so you could try that. You could try and work out your cycle based on the date of your last period or if you have already started taking the EstroGel, opt for any day. If you haven’t already started, start the EstroGel and count day one of EstroGel as day one of your cycle and then start the Utrogestan on day 12. I hope that helps.