When should we begin to address our child’s behavior?

As soon as a child is old enough to push limits (being told no and reaching in to pull dirt out of a plant) they are old enough to learn consequences for getting in another’s space (yours). We began with slapping little hands – then moved to spanking for obvious acts of rebellion (your Proverbs passages you listed – Proverbs 13:24 and 23:12-14).