Please help.

My boyfriend and I were staying at a hotel and we always use condoms. Well, on Saturday I got my period but It was light. You know, like you usually do before the actual heavy flow comes. Well, call us stupid because we both got drunk and we ended up having sex without a condom. He didn’t cum but obviously there was precum. Should I still take the Plan B just Incase? My next fertile window is 3-10 if that helps.