What are the chances

My boyfriend and I had unprotected sex for the first time. We usually use a condom. It was the last day of my period and I had started my birth control that morning. He did not cum in me, before he even came close to that he made sure to pull out. But what are the chances of getting pregnant from pre-cum? And before anyone says anything about plan b, it’s already past the time limits that I could take it.