Moving past judgement, which is useless (sure everyone should always use a condom, yadda yadda, personally guilty every so often of failing to use common sense in matters of lust & love)...
There isn't any way to determine the "chance" of her being pregnant, either she is or she isn't. The bleeding issue is meaningless, since it's common both for women to experience irregular periods or bleeding after sex (esp for the first time), and it's possible for women to have short menstrual cycles after becoming pregnant.
Real talk, tell him to do the following things:
1. If it hasn't been at least a week, just wait and hope for the best. Tell him to use this time to make sure he's had "the conversation" about her feelings on the issue of abortion and her options if she should become pregnant.
2. After a week, take a home pregnancy test. If it comes up positive, go to the doctor. If it comes up negative, follow up with a second home pregnancy test in 1 week. Two negatives and you're pretty much in the clear.
3. Remind him that the is an issue that everyone who has sex must experience, and that it is her first time so he has a great responsibility to be a support to her during this time. It is always important to keep the consequences in the back of your mind when you choose to have sex, even with a condom. If he hasn't had the big abortion talk, if he isn't ready to potentially stand up and raise a kid if that's what she wants, there are other ways of expressing love between sexually active couples that don't make pregnancy an issue.
God speed, keep us updated if there is news...