If your mare does indeed foal at the end of February, the foal will be 3 months old at the end of May. That is the earliest recommended weaning date and I have done that on numerous occasions with mares that are being campaigned. You would have to make sure the foal is on a very good nutrition program to do that. If I were you, I would look at weaning the foal as early as your vet recommends.
Whatever you do, you'll have to make sure the foal and mare are accustomed to being separated before you go to the show. Having the foal on the sidelines might be a greater distraction than you think, unless the foal has a surrogate companion to keep him company. The worst thing would be if the foal and mare were calling back and forth to each other. Often, "out of sight, out of mind" is a better solution.
I would start separating the mare and foal for brief, but increasing periods when it is about 2 months old. Make sure the foal has some company, another mare and foal would be ideal, but any horse could be a companion. Leave the foal and companion in a stall while you work the mare, so they both get used to separation (preferably out of sight and ear shot). Then at your first few shows, take the companion and leave the foal in the stall with the companion while you show.
Also, look at weaning early and putting the foal on a good nutrition program plus high quality grass/alfalfa mix and a vitamin supplement. I feed my lactating mares a fortified feed from their last three months of pregnancy through weaning. That way the foal is eating the grain from very early on and gets an increasing amount of its nutrition from the feed instead of the mare.
Good luck with your show season!
Julie Goodnight
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