1st 3 years of a child

"Let selfishness, anger, and self-will have its course for the first three years of a child's life, and it

will be hard to bring it to submit to wholesome discipline. Its disposition has become soured; it delights in having its own way; parental control is distasteful. These evil tendencies grow with its growth, until in manhood supreme selfishness and a lack of self-control place him at the mercy of the evils that run riot in our land."
Mind, Character, and Personality vol. 2, p.516 E.G.W.

My son, despise not the chastening of the LORD; neither be weary of his correction:

For whom the LORD loveth he correcteth; even as a father the son in whom he delighteth.

Proverbs 3:11,12