If this is going to be his first race, let it be a fun race without the pressure of winning (which is unlikely) due to the learning curve of more than just riding a bike.
There is the start to learn, holding lines, protecting his lines, riding very close to others, endurance at race speed and more. Let him make as many practices as he can and repeat to him that practice is not a race, there are no winners.
Good luck, have tons of fun, take pics and share them with us.