The best time to cultivate children's behavior habits is when they are young. This period is called "critical period". In the critical period, the child's brain develops rapidly, and his learning ability and imitation ability are very strong. Through proper guidance and education, they can be helped to develop good behavior habits.

Here are some examples of key periods:

1. Birth to 3 years old: This stage is the fastest period of children's brain development, and it is also a critical period for establishing parent-child relationship and forming safe attachment. Parents should spend more time with their children, meet their needs and help them build self-confidence and security.

2.3 to 6 years old: At this stage, children begin to learn to communicate with their peers and form a sense of friendship and cooperation. Parents should educate their children to respect others, learn to share and wait, and cultivate good social habits.

3.6 years old to 12 years old: At this stage, children's thinking is gradually mature and they can understand rules and constraints. Parents should educate their children to observe discipline and develop good study habits and time management skills.

4. 12 years old to 18 years old: At this stage, children gradually form the ability of independent thinking and judgment, but they still need the guidance and support of their parents. Parents should educate their children to take responsibility and cultivate their ability to solve problems and deal with stress.

In short, the cultivation of children's behavior habits should start from an early age, and grasping the critical period for education and guidance will help them become people with good quality and social adaptability.