I think every wrestler in their early matches have extreme nerves. Call them what you will, “butterflies in your stomach”, “Being nervous”, or whatever, but I think the key difference between a confident wrestler and a not so confident wrestler is to figure out the difference between nervousness and letting the adrenalin fly.
Being nervous, in my opinion goes away with the harder you work. If you’ve put in the hours, than you have much less to worry about. If you look across the mat during warmups, and you can honestly think to yourself, “Well, I know I have at least out worked this punk” than you leave the nervous zone and enter the adrenalin zone.