Many companies will hire him at 22 or even 21 years old. Tell him to go ahead and start CDL school. He can start applying for jobs as soon as he is attending classes.
You can check the company listings on this and other trucking forums for basic requirements of some of the larger carriers. You can legally drive a class 8 truck in interstate commerce when you are 21 years old. The problem is insurance. He may find a job before reaching his 23 birthday, but I would do some checking before spending money on schooling. Smaller carriers will find it difficult to insure him at his age and with no experience. Larger carriers have their rules. He will probably not be that far from his 23rd birthday by the time he completes his schooling. I believe you stated that he is currently 22? If I were spending my money, I would want to make sure that I could find a job as quickly as possible after graduation. If you can time it where he will have his birthday prior to or shortly after graduation, his options will be much greater. Good luck.
Here are a few of many companies that hire at 21: Many companies have tuition reimbursement for CDL school. Navajo Maverick Howard Transportation trans-system (maybe 21)
im 20 and got my class A when i was 19 my biggest issue is not meeting age requirements for company insurances a good chunk are 21+ and alot of major ones are 23+ he should be fine and companies love clean MVR's local companies construction,paving, sand and gravel companies its the experience he will need to focus on getting in the years(2-5) after he gets his CDL