Many toddlers are ready for toilet training after their second birthday, but early training is possible with some children. Children capable of following directions, who show an interest in imitating family members in the bathroom, who experience bowel movements on a regular schedule, and who have a diaper that is not always wet may be ready for toilet training. Although early potty training is convenient, it may place unnecessary pressure on a young toddler and is generally accomplished more quickly with older children.
Shelov, S. P. (Editor-in-Chief). (2004). Caring for Your Baby and Young Child: Birth to Age 5. The American Association of Pediatrics. Revised edition. New York: Bantam Books.