How to tell parents?

My boyfriend and I are having an unplanned pregnancy. We have been dating for 4 years now (on and off at first now steady). I'm currently 12 weeks pregnant and we decided that babies are blessings and that we would not find the easy way out. We know the consequences of premarital sex. Anyways, we are both 22 - haven't graduated college yet and are working part time jobs. What's the best way to tell parents that you are expecting? Should we tell them together as a couple or separate?