I think the best thing you could do is to come out to them before they meet him. While I really hope that your parents are supportive and absolutely lovely about your relationship, there is always a risk of them having a bad reaction. If I was in your boyfriend’s position I personally would not want to be in a place where I was in the middle of a family disagreement, especially if it was my first time meeting them. Likewise, if you are sure that your parents will be supportive I would wait until you come home to come out; most parents expect that their kids will have more of a love life than they did when they lived at home. Therefore, I would carefully bring up the fact that you’ve found new close friends at uni and possibly a new relationship to gauge a reaction; if it seems positive then I would slip in the part about having a boyfriend and go from there.