After school, I was in some "advanced" schools for a better graduation. In the 11 and 12 class, we had a subject programming. From 14 classmates, had always huge problems and could not resolve a task without help. In this classes, all were about 17/18 years old.
I think it´s a good idea to teach children programming because for me it changed they way I think.
In conclusion, it depends. It depends on what language you want to teach and how motivated the children is.