My son is already well on his way. He already knows most of the tools by name. The set-up at our house in Denver was much more conducive to having the kids in the shop with me, though. We had a detached garage and I built the fence to enclose the garage and driveway within the back yard, so I could have the garage open and keep an eye on my son while working on the bikes, and he could come in and hang out with me when he wanted.
Now we have a more typical set-up where the back yard is separate and the garage and driveway are open to the alley, so I can't keep an eye on them if they're in the yard, and I can't let them run free if they're in the garage with me.
Luckily, by the time either of the bikes needs a major overhaul again my son should be old enough to actually help, if he wants to.