When does ovulation occur?

I had my period on Dec 6- Dec 10/11. Before that I got my period in September but I had unprotected sex and took a plan B. I usually get my period in the beginning of the month. I had sex yesterday and he finished inside of me which was a mistake. I took a plan B. It says I’m scheduled for my next period on Jan 7 6th. When would I ovulate? I don’t think I’m ovulating right now so I’m hoping the plan B worked.