My advice: make sure he has other interests and socializes.
I was obsessed with coding from age 7, and now wish I had spent that time otherwise, more being a "normal" kid and less time sitting alone giving orders to a damned computer. Once I reached my mid-twenties the joy died in the realities of the job market, and now I can't even think about that crap anymore.
You know what I enjoy now? Playing a guitar. Didn't start until age 30, and it was like a revelation.
Sorry I didn't answer your question. I still think any parent who wants to "get their child started" on something early should heed my advice and experience. I am for real a walking, talking (sometimes) warning.