A puppy's developmental milestones follow a fairly predictable timeline. By 2-3 weeks of age, puppies' eyes open, and the crucial period of socialization begins around 3 weeks and continues through about 12 weeks. Sexual maturity is reached at approximately 6 months in many breeds. The critical socialization period, often described as 3-14 weeks, is when experiences most profoundly shape a dog's lifelong temperament, making early positive exposure one of the most important investments a new owner can make.
Socialization should include careful, positive introductions to a wide variety of people, animals, environments, surfaces, sounds, and handling experiences. This exposure differs from training, which involves teaching specific behaviors on cue. While socialization builds comfort and confidence with the world, training builds reliable skills. Both are essential, but they serve different purposes: a well-socialized dog who has not been taught basic manners can still be difficult to live with, while a well-trained dog who was not properly socialized may remain fearful or reactive in new situations.
A startup checklist for a new puppy typically includes scheduling a veterinary appointment, gathering appropriate supplies, fitting an ID tag, planning a training program, designing a socialization plan, and preparing a safe space in the home. Another important early skill to nurture is bite inhibition, the learned ability to control the pressure of one's mouth. Ideally taught during puppyhood through gentle feedback when teeth touch skin, this soft-mouthed control is far easier to develop early than to teach later, and it remains one of the most important safety behaviors a dog can learn.