Most dogs start to become sensible around 7-8 months. But each dog has a different personality, so this is also affected by factors such as breed, age and training.
Generally speaking, most dogs will become steady when they become adults and will have a quieter and gentler personality, especially the breeds of golden retrievers, border collars and bichons, which are more gentle in their own personalities. But there are exceptions. For example, the Labrador is a late-mature type. It usually becomes calm after the age of 2-3, and 1 year old is the most naughty time.
If you want your dog to become sensible, in fact, the owner should start doing some simple training at the age of 3-4 months, such as instruction training, fixed-point bowel movement training, and follow-up training, which can increase the dog's obedience to a certain extent and better regulate the dog's behavior.