hi there, usually menstural blood flow is due to a delicate hormonal
balance in our body and usually you get mensturation when there is withdrawal or decrease inlevel of one of the hormones. Taking a high dose of premolut for five days and eventually stopping it produces the same effect of withdrawl which cause mensturation to start. Usually they start on 2nd or 3rd day of stopping the medication. So you should also get it after a 2-3 days of stopping the pills.Take care.