Now, that's some good advice. Pace yourself. If the curtain goes up in a half an hour, then don't get more than thirty minutes worth of nervous.
You've heard of this strings program in New York, right? If you haven't, then watch this. These kids, and their amazing teacher Roberta Guaspari-Tzavaras at the Opus 118 Harlem School of Music, work hard to contribute something to the music of the spheres. They contribute beauty. If you can, contribute money to them so they can keep it up. (The Meryl Streep movie about Roberta is called Music of the Heart. That's how I found out about these people. I cry every time I watch it, because the heroism of people who believe in the courage of children always makes me cry.)