Plan B 1 - 2 hours after

My girl and I had sex on the day before she started ovulating. The condom from the tip broke and she hopped of real quick, but we were at least 7 to 9 min into it. I hadn't been close to busting at all but since i know somethin about a little bit of precum, we bought plan b the same day and took it within an hour or two. Can plan b be really effective at this point?