Your first competition
My son plays his first ever music competition tomorrow. He is 6.
Can you remember when you had your first competition? And how did you feel?
Any advises, how to help him?
He's six. Encourage him to play his best as you would for any performance, and do not put any pressure on him for results. And definitely do not "suggest" to him that he will be nervous, or that he should care about the outcome beyond striving to do his best.
My first competitions were "Solo and Ensemble Festival" events. I never placed, but you get a score and a tiny medal if you play well. I always got a medal, and one of the comments was the same, year after year: "Intonation needs work." That's because my teacher, I learned 30 years later, never taught me this properly. He never taught me to listen to "ring tones" on my instrument. He insisted instead that my intonation would get better on its own. My parents and I were too ignorant to know how bad that was.
Your kid will pick up on your anxiety. Try to relax as much as you can. Don't make a big deal out of either a win or a loss. And don't expose him to either kids or parents who seem very invested in the outcome.
I remember myself my first big regional competition in gymnastics. I was 6.
I was about 15 when I was first entered in the local music Eisteddfod, won my class and had to perform the first movement of Mozart 3 in the final concert. Nerves, what nerves? I can only speak for myself but I think until parents get too involved a kid's default attitude is, let it rip! A year or two before that I'd made my operatic debut in a one-act piece by Kurt Weill and followed it the next year singing Polly Peachum in the Beggars' Opera. Still have a recording on a 10" LP!
You could help him by not putting him in competitions at this age.