Age Gap, Telling & Meeting Parents, and Moving

I'm 17 w/ a 21-going-on-22 year old boyfriend. I've known him for 2-3 yrs (with us being basically attached to the hip while denying any feelings) & my mom has seen him more than a couple of times, but doesn't know him. We're now being serious about each other and wanting to be together. He wants to meet my mom & dad. I'm caring more about what my mom has to say because I actually live with her & she's my legal guardian.. I thought about telling her about him on my 18th birthday but there's a catch. I plan on moving to Atlanta with him, a guy that's like my brother, and his girlfriend after I graduate which is only a month after I turn 18.. I'm scared that she's going to be pissed but I'm deeply in love with him.. I don't want to have to choose. How should I go about telling her & when.?