You're more likely to get pregnant around the time you ovulate,however there is still a risk at anytime. You protection if you do not wish to become pregnant.
Anytime you have unprotected sex, you run the risk because even if you did not ovulate on the 12th, if you ovulated anytime up til the 17th, you could still have become pregnant. There is no safe time for unprotected sex except when pregnancy is wanted, of course.