Time to take progesterone during cycle.

I hv irregular menstrual cycle of more than 35 days since last 2 mths last mth I induced periods by deviry 10 mg I visited a nearby gynaec c sugested me to take progesterone pills for 10 days that is day 11 to day 20 of my menstrual cycle so that I can get my periods on time i just wanted to know that from which day of my cycle should I start progesterone pills to get my periods on proper time coz if I take progesterone from day 11 to day 20 won't i start bleeding on day 21st only due to breakthrough bleeding Plz help and guide me coz I m planning to conceive so I want to keep track of my ovulation time Also I wanna mention that I got a abortion done 2 yrs ago Plz help me specially about timing of progesterone pills I would really be thankful