Marriage Proposal

So my fiance and I have been dating for more than a year and I finally proposed to her.

I am 23 and she is 22. The problem is that her parents don't know. Her dad is former military and is a hard ass.

She is currently still in college and will be for at least another year. We are going to break the news to her parents over dinner this weekend and I'm trying to make her parents understand that I can take care of her and provide for her while she is still in school.

I'm trying to figure out what is the best time during dinner to break this news and what should I say exactly to make them understand. Please help