What is the apt Age for learning Abacus based Maths?

•The greatest growth of the human brain is during 4 to 14 years old whereby during this period, the frequency of the brain waves increase gradually from theta (relaxing stage) to the alpha level (relax but conscious). Children in the alpha level are full of imagination and have quicker learning ability.

•According to an analysis on the development of nervous tissues, the development and growth of the nervous system begins from 4 to 6 years old with the quickest speed