Better to have more than you need than not enough - so I would take more than you think you need. I can't tell you a specific amount as I don't know the venue, the traffic, how long the show is, etc. Everyone is nervous for their first show, but you'll do fine. Use the tips in this article and check out the resources listed and everything will be fine. You'll learn as you go, but other crafters are very friendly and will help you out.