Boyfriend spilled he’s going to propose to me while drunk!?

My boyfriend (20) and I (19) have been together for the past year and a half. We’re both in our second year at uni pursuing two different medical professions, and I’ve been living with him in an apartment since this past fall. I’m happier than I’ve ever been and we complete each other, we both are hardworking goal oriented people, but this took me aback a little. On New Year’s <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a> I didn’t get completely drunk (I had a few shots and some wine) but my boy drank more than I think I’ve ever seen him drink, and right before we passed out he opening up to me about what my “late Christmas present” is, our mutual friend is traveling overseas right now and he paid him to get me this diamond engagement ring for me. He then started crying and telling me how we’re going to get married. The next day he didn’t remember telling me but I remembered but haven’t said anything because while he was drunk lamenting he was upset he ruined the surprise. I felt so happy and in love but now reflecting on it I’m afraid that we are too young. How do you know when it’s the right time to get engaged?