When can I start limiting privileges as a disciplinary technique?

Discipline. Until a child is about 3 years of age his thinking brain is not developed enough to use reason such as with holding privileges as a technique. Discipline until then need to be based on rewarding good behavior and seen as an opportunity to teach. Never use withholding your emotional connection with your child as a disciplinary technique but do set limits and be consistent.
3 years. For most children, time-outs are the best form of discipline from 15 months to 3 years old. Redirection can also be used for younger children. After the third birthday, children can start to learn other consequences for their actions, including limiting privileges.