How To Postpone Menstrual Cycle Inspite Of Being On Femilon?

Hello,i have been taking femilon since 3-4 years.this time I want to delay my periods for a week.I got my periods on 20 feb and my cycle is 28 days.i would get my period on 21 March.i finish my tablet on 17march so 21st ill get down.shall I start my second strip of femilon.plz suggest. Thanks