At how old do Japanese start to learn how to use chopsticks? How many years does it take?

Question:
At how old do Japanese start to learn how to use chopsticks?
How many years does it take?
Answer:
When kids start to eat by themselves, they try to use chopsticks.
At first, they just grasp chopsticks, but a couple years later they can operate them well.
Pic: http://ctrl-0.com/photolog/?cat=23