My granddaughter will be 3 years old in 2 weeks and she flies my simulator better than I do! hahaha

But, she'll see the cat at the corner of her eye and will drop the radio and go chase it...

Some have a longer attention span then others, and some have better dexterity too. There's a 12 year old at the club I used to belong to who flies the large warbirds and does so very well.

So it all depends on the child.

The advice from Insanemoondoggie is the best to follow IMO.