How Many Days Should I Take Duphaston To Have Period?

hi, i have an irregular period. last oct 2010 to feb 2011 i took pills to have a regular period. and by march i did not took pills and i had a sexual intercourse by then month of march up to now i didnt get my menstrual cycle. and pls. take note i also have interocurse by the month of may. and by last week i started take duphaston... 10 days 2 times a day 10mg. how many days the effect of duphaston to have my period. my 10th day of taking the med is tomorrow. thanks!