It also lays a good foundation for you to talk to the show farrier if you can lead with a gush of praise from your own farrier. Beware of farriers who insist on making drastic changes in your horse's shoeing. They might have perfectly legitimate reasons for suggesting a special device, but your goal in having the horse worked on is to get through the show with a sound horse. If there is a problem, you can have it worked on at home, by someone who knows your horse and his history. It might sound obvious, but ask a show farrier ahead of time how much you can expect to pay for the shoeing and what the payment arrangements are.
Most farriers like to be paid in cash, particularly when dealing with strangers.
There are many advantages to having your horse shod before you leave home. One that you might not have considered is that your horse will be shod in front of a critical audience at a horse show. Three or four idle farriers and owners might stand around and critique your horse's conformation, your tack, your horse's bloodlines, or the current shoeing as if you weren't even there. This can be unnerving, not to mention rude. But it happens all the time.