My eldest is 7, and has got into modelling as I have got back into it.
His first project was to finish an ancient Matchbox Victor which I had started but never finished. With that under his belt he bought a little revell 1/144 Sukhoi berkut, and had not looked back since.
So far he has built everything from a P40 to the Bismark, all of which he has done himself, with me providing advice where required, as well as glue and paint.
last weekend I let him and my youngest son, 4, loose with my airbrush. both of them showed considerable control just painting a peice of paper. think I know whet my eldest will want next!
As everyone has said so far, it's best not to push them, just let curiosity run it's course.
Karl