Mom flying out

Emily
So I'm due on Feb 12, and my mom is trying to figure out when to book her flight to come here (NY to TX). Since it's not a cheap last minute flight she wants to book ahead and is hoping to be here for the birth. We decided to have her come when I turn 39 weeks (Feb 4th). This is my first baby, so I'm assuming I'll be at least my due date if not late. Do you think this is a good time to cover in case he comes early? I know there's really no way to predict when he's going to come, so we're just trying to figure out a middle ground where if he's early she's not too late coming and if he's late she's not sitting here for weeks taking up her vacation time waiting for him. She said she's worried because he's "low" and everyone's telling her by my pictures and how low he is they don't think I'll be more than another month but I'm trying to tell her that him being low doesn't mean he'll come sooner.