What you want to ask is "at what age are children suitable for behavioral education"? I think we can start watching behavior education at the age of two.

At the age of 2, children have begun to have independent consciousness and cognitive ability. At this time, their psychology and character can be shaped. The germination of advanced cognitive activities has changed children's cognitive ability, which is also the first turning point of psychological development. At this time, parents began to give bystander education, which will be of great help to the psychological development of many children in the later period.