Toilet training generally starts when a child shows signs of readiness, which usually occurs between 18 months and 3 years of age. Most children are ready around 2 to 3 years old, although some may be ready as early as 18 months. Important signs of readiness include being able to stay dry for about 2 hours, showing awareness of wet or dirty diapers, expressing interest in using the potty, following simple instructions, and being physically able to sit on the potty and pull their pants up and down. It is also recommended to start toilet training when the household environment is calm, without major disruptions like moving or having a new sibling, and the caregiver feels ready to commit to the process. Starting in warmer months can be beneficial since children wear fewer layers, making it easier to undress. In summary, wait until clear physical and psychological signs of readiness appear rather than focusing strictly on age, and choose a calm, consistent time to begin toilet training.