Confused

I was having sex with my boyfriend and the condom broke, in the morning he got me plan B and I took not even 12 hours later, I took it around the time I was ovulating it was 2 days before. I don’t know how plan b works ( I mean I do) I just don’t know when it kicks in ? It’s been a week and still no signs of it kicking it? I just wanna know what you guys have to say on this.