Probably not. And if it's been over 72 hours the pill won't work.
Any time you have sex, you can risk becoming pregnant, which is why you should be using protection every time you have sex. That said, for most people, the day before they start their period isn't their most fertile time so it's not most likely you would become pregnant in that time. However, sperm can live in there for up to 7 days in some cases, so if you ovulate early, then it's possible to conceive. All you can do now, is wait until your next period and if it's late or off then take a test.