بسم الله الرحمن الرحيم
(Fatwa: 1032/805/B=1434)
If you are sure that you did intercourse with your wife before the starting of haiz (menstruation) then there is no sin. If she experienced haiz after the intercourse then too there is no sin. It is sin to do intercourse in the state of haiz.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband