A child at the age of 6 completes 70% of learning in life. I have read some where that creativity is best between two to four year of age which may be up to 95% and at age six, it falls down to 5%.
Catch thy young.
Younger the child, easier and proficient to learn meditation.
A child's mind is like a clean slate, nothing much has been written on it. It is extremely easy for a child to learn and become proficient in meditation.
Once the learning and habits are formed, it is very difficult to undo them.