I started being interested in programming and also cryptography a year ago but I started learning it three months ago.
I'm fifteen years old now and people think I'm too young to learn and know things about programming therefore I searched on the internet to see the chances I had to learn programming using my computer. Fortunately I found codeacademy. I've been loving codeacademy material and courses.
Children should be encouraged to learn this because the sooner you learn, the sooner you'll start producing.
I just want to say that If you have young kids you should stimulate them to give programming a sout. There is a chance that they don't like it but if they do, they will definitely get advantages from learning it.