How To Postpone Periods?

sir, my period was to be started on 10th of this month but it didnt. Its my marriage on 26th of this month. So i dont want my periods to come back around 26th. My doctor has prescribed meprate to postpone periods and i had one tablet today night. Shall I know whether there is any chances for periods to come back tommorow? Is there any side effects for meprate? how many days i can postpone my periods with meprate since my periods date is past by more dan 7days?