Before you ovulate yes because as ClaireDeLoon says sperm can live for a few days. However, once you have ovulated the egg is only able to be fertilised for a day or two and whatever you do after this time will not get you pregnant.
Seems I am ovulating between day 8 and 10 so it can ne very early in the cycle. The only sure way to know us to chart/ use opks. Safe to say, if you don't know when yore ovulating and you.have unprotected sex, you could well get preggers!