I agree with PaulCyp. Discipline or abuse should never be applied to any three month year old. They would never understand either. They will only damage the child's future and their love for you. Children probably don't need discipline until at least when they can walk. And even then it should be mild. Only when they are older can they be disciplined and by no physical means should it be done.
Discipline is a method to guide behavior. Learning how to study properly is a discipline. Children need to have limits set, but those limits can be set by frowns, finger wagging, raising the voice, etc. Abuse is unnecessary, cruel, and counter productive.