Can i start minigynon on the third day of my period?

Yes: If this is your first pack of oral contraceptives you should take your first pill as soon as possible after your period starts. Most packs are set up to start on a Sunday but starting the first pill within the first 4 days of menses assures that they will provide birth control during the first month of use. Otherwise you cannot rely on the pill until you start your second pack.