Stages

6 weeks.....

9 weeks.....

11 weeks.....

13 weeks.....

14 weeks.....

16 weeks.....

20 weeks

6 Months

7 months......

8 months......

11 months......

Here are the periods in a dogs life per say.
Keep in mind that all dogs are individuals and don't read books so some of
the timing for fear periods can be off.

Neonatal: Birth to 12 days (Obtain nutrition and stay warm)

Transition: 13-20 days (Eyes open but not seeing well until 21 days, puppy
can crawl backwards and forwards now, begins to walk,first teeth erupt aroun
20 days, tail wagging begins, reacts to sounds around 19 days but cannot
locate source, moves bowels without stimulation.)

Awareness: 21-28 days (First week puppy is able to use sight and hearing.
This change happens abruptly so a stable environment at this period is
critical. Can psychologically scar puppies if moved to new location. Pups
have greatest need for mother and familarity at this time. Learning begins in
this stage, it is time to begin learning what it means to be a dog.)

Canine Socialization: 21-49 days (3 to 7 weeks) (Puppy learns to use species
specific behaviors that make him a dog. Practices body postures, facial
expressions, and vocalizations and learns their effects on siblings. Plays
chase games to learn coordination and timing, greeting behaviors to learn
body postures and fight games teach him use of his body. Learns to accept
discipline during this time from his mother. Learns bite inhibitions and
weaning. Mother dogs set up the puppies for these lessons. Very important to
let mother dog stay with pups to teach these lessons.)

Human Socialization 7 to 12 weeks (Best time for bringing pup to new home.
Best time to introduce pup to things (in a positive manner) that he will be
exposed to. Brain waves are same as an adult dog at this age. Most rapid
learning occurs. LEARNING AT THIS AGE IS PERMANENT. )
First Fear Impact: 8-11 weeks (Any traumatic, painful or frightening
experiece at this time will have a more lasting effect on the puppy then if
the event happened at any other time. Puppys perception of the event is
important not owners. NO elective surgery should be done at this time. Puppy
classes at this age need to be non-stressful for pup.)

Senority Classification: 13-16 weeks ( Also known as age of cutting teeth and
apron strings. Pup begins testing to see who is going to be pack leader. From
13 weeks on if puppy attempts to bite even in play it is an attempt to
dominate. Pup is attempting to clarify and resolve the question of
leadership. Establishing rules for pup extremely important at this time.)
Flight Instinct: 4 to 8 months ( Puppy begins testing his wings of
independance. May suddenly begin not coming when called. Puppy still
teething. Adult teeth come in by 6 months but not set into the jaw until 10
months. Still has a need to chew. )

Second Fear Impact: 6 to 14 months (Corosponds with growth spurts. May be
frightened of new things or even known things. Don't reassure dog-it teaches
the dog to be fearful. Don't force dogs into fearful situations. Ignore scary
thing so dog wont be afraid. Use treats and positve methods to coach dog
through event. Any training classes begun at this age needs to be fun and
non-stressful for the dog.)

Maturity: 1 - 4 years (Can be marked by an increase in aggression and a
renewed testing for leadership.)

That is originally from a book by Joachim Volhard and Gail Tamases
Fisher called Teaching Dog Obedience Classes

Physical and Mental Growth Factors

Visual Physical Growth Stages