My periods are due on 16 n its my d day.. I want 2 delay so if I take this tablet PREMOLUT-N so how many day before my date I should start?

You shouldn't delay your periods. Having a period is normal. It is a reason that our bodies as women have periods. The blood is leaving your body for a reason. That blood is cleaning out your uterus. It is unclean and you don't want to keep uncleaniness in your body because it can turn toxic. What happens when the body gets toxic buildup? It gets sick.