when to start using OPK after AF

Hey everyone, I got married a week ago and stopped birth control just before the wedding. My husband and I have been talking so much over the many months/year leading up to the wedding about TTC and I just have a question. I have been taking my bbt every morning but how soon after I start AF do I start using my opk? AF came about a week early but it's her first visit since my BC so I know my body might be out of whack for a bit. I just want to start gauging my body. Thanks!!!!