Missed Pill – How long until I’m protected?

Patient: I’m a first time user of BC and I’ve been on Levlen ED for a month now. Yesterday I forgot to take the pill at my usual time of midday-1pm, and so i woke up today and took the pill i’d missed at around 11am, and then went on to take my usual pill at 1pm. I had unprotected sex yesterday but the guy didn’t finish, and now I have nausea. How long until I am again protected from the risk of pregnancy?