Plan B day of positive OPK

We are not trying to have a baby right now I’m only 3 months postpartum. I’m currently not on birth control because of medical reasons so I track my ovulation to prevent pregnancy. Last night we had sex without protection or prevention and today I took an ovulation test and it was positive. Will a plan B still work if I take one today?

We were in the moment and oops. 🥴

Edit: Well I took one. Let’s see what happens. 😅