When Should I Expect My Period When I M On Day 4 Of Taking Duphaston For Delayed Period?

Hi,I have a normal period which usually start from 27-31st, but my last month period was on 33rd which is still normal. I m yet to see my period for this month and it s more than 35days now tho my pregnancy test was negative. So my doctor prescribed duphaston twice daily for 10 days. This is the 4th day, when I m I supposed to see my period or I m i pregnant?