yes of course it doesn't matter if it's the first time or not. if you pulled out before then that would have lessened your chances, but i would still suggest plan b if its within 24-48 hours.. or it might be 72 im not sure. either way she needs to get on birth control also..you can usually get it for free at planned parenthood or a health department.
What worrieddd612 said is correct, and also, Plan B can be taken within 72 hours, but the closer it's taken to the time of unprotected sex, the more effective it is. However, you and her being only 15, you'll either need a person over 17 years of age to get it for you, or a doctor's prescription.
It depends. I live in Ontario, Canada, and I went shopping at the drugstore two days ago to get some HPT's, and was shocked to see plan-B right there with them. I think that is a great idea though, since it needs to be taken asap. My test turned out positive, and cant get into doc's until next wednesday..Would have been way too late if thats what I needed..