I had unprotected sex 3 days ago, and today I got my period.
Is it possibility that I can get pregnant?
What are the chances?

If your period arrived on schedule, odds are very low for pregnancy... possible, but unlikely.

Many women will ovulate about mid-cycle; some a bit sooner, some a bit later. While it can happen to have an off ovulation from your norm, it is not common. Certainly protection should be used every time to decrease the odds even more since there is no 100% safe time... only some that are "safer" than others.

Yes. It is possible that you get pregnant..