What do you think?

Yesterday (31st, less than a day after period ended) I had unprotected sex using the pull out method and it failed. The thing is tomorrow, Nov 2nd, I'm getting Nexplanon inserted. I've read that it is uncommon to get pregnant before ovulating and my fertile window supposedly starts on the 5th. Would the Nexplanon help in any way to stop fertilization before I ovulate? Has anyone had sex right after a period and become pregnant?