I understand being anxious when they're overdue, but frankly there's really nothing your vet can do until it's time. And one day over is really nothing at all. Give her a week before you start getting really anxious, and she oughta have it within three more days after that!
The best thing you can do is keep a close eye on her. Within 12 hours before labor, she'll start latent labor, and she'll look for a quiet place to be alone and separate herself from the rest of the herd. Pay attention to her behavior...what's normal, if she seems anxious or alert...and try to see her at least 3 times a day if possible. Every 4-6 hours is ideal if you're really nervous about this, but that's not always possible.
Labor for a mature cow shouldn't take more than two hours, but that's after labor actually starts. If you can be around and feel pretty comfortable about when she starts, you'll know if/when it's time to interfere. Everybody will be better off if you don't jump the gun and get involved unless you need to. Instead of getting anxious or giving in to fear, keep your head, use your common sense and above all else, trust your instincts. Most of us humans have learned to react to fear instead of instinct, and fear is not a good guide in this type situation.
Good luck! I'll start calving about 30 head in a couple weeks, so I may need you to send me my advice back to me when I start getting anxious to see babies on the ground!
