I was 18 when I started. Wasn't sure what would happen, a year after 9/11.
Here is the way I look at it. You'll love flying or hate it. If you don't love it, dont do it. here is the way I look at it:
I think there will ALWAYS be a job for a pilot. How good that job is is the problem. I made up my mind when I was VERY young that this is what I wanted to do, and under an circumstances I will do it. My goals are be a CFI for a few years, fly for a small cargo operator or regional for a few, and go work for UPS. Is it going to happen like that? 98% NO, it will not. Accept the fact that in almost all cases it will not work out the way you plan, and live with it. That is my goal though. He will have to do something similar to that. I assume he wants to fly for a major one day, since thats most of our goals. guys on here know better than me, but I have been told competitive for a major job is about 4000TT, with quite a bit PIC jet time of that. At 19, I say goal wise shoot for early 30's until you reach that. If it does not work like that, then so be it. Accept that, and fly becuase you love it. I think with all the cost and sacrafice flying involves, be committed for a career in aviation no matter what. Some may disagree with me though.
[email protected] if you want a young perspective. The advice and years of expirence on this website though is highly valuable, and your son should read through the info here often and decide if its what he wants.