The Prophet (peace be upon him) instructed, "Command your children to pray when they are seven, and discipline them for it when they are ten, and separate them in their beds." Before seven, the emphasis is on gentle habit-building and example rather than command, and even the "discipline" at ten is understood by scholars as light and corrective, never harmful or humiliating, since the goal is to make the prayer beloved. The aim across these years is to build a child who prays out of love and habit well before it becomes obligatory upon them at puberty.
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.