Hello Thanks for writing to us with your health concern. Thanks for writing to us with your health concern. IT is much more reliable to postpone your periods rather than preponing them. Let me explain how this works. Say your expected period is on the 15th. If you want to prepone it on the 4th, then you need to do this - Progesterone preparations ( Deviry, Sysron - N, Primolut - N ) are commonly available in the market. The dosage is guided by your body weight , history etc, it is best to take them after consulting a gynaecologist. Generally 5 mg twice a day is taken for 5 days. Once you stop, you bleed within 7 days anytime. SO preponement is not a certainty, however for postponement, you can take them 2 - 3 days before your expected periods, and then stop on the date you are safe, for eg, start them from the 12th onwards till the 15th, once you stop, you will bleed within a week. All the best Take care.