To clear up some confusion on the Dan ranks reagrding minimum times
for each rank:
**see "Titles" post for explanation of Dan ranks**

Shodan (1st Degree)- We have yet to decide on a minimum age. It will
probably be somewhere between 12 and 16 years of age. There is no
specific time frame on how long it takes to become a Shodan however
usually on average it takes 2 years. This depends on how hard and
how often you train.

Nidan (2nd Degree)- Must be a Shodan for a minimum of 1 year before
you can test for Nidan.

Sandan - Must be a Nidan for a minimum of 2 years before you test for
Sandan.

Yondan - Must be a Sandan for a minimum of 3 years before you test
for Yondan.

Godan - Must be a Yondan for a minimum of 4 years before you test for
Godan.

Rokudan - Must be a Godan for a minimum of 5 years before you test
for Rokudan.

Shichidan - Must be a Rokudan for a minimum of 6 years before you
test for Shichidan.

Hachidan - Must be a Shichidan for a minimum of 10 years before you
test for Hachidan.

In short you must be a black belt for a minimum of 31 years before
you can be promoted to Hachidan (8th degree black belt).

Kudan is only awarded to school founders who are a minimum of
Hachidan after a life time of involvement in the martial arts.
Although there is no set time it's usually 50 or more years of
training.

Judan is awarded honorary to founders of a style or to Kudan
instructors after their death (or right before they die).

As far as the times for titles go...

Renshi - must be a Yondan for a minimum of 2 years. This title would
be similar to Bachelor of Arts.

Kyoshi - must be a rokudan or renshi for a minimum of 2 years.
This title would be similar to a Master of the Arts.

Hanshi - Must be a hachidan and a minimum of 50 years of age and must
already have kyoshi title. This title would be similar to a Doctor
of Philosophy.

Soke - it's not awarded, only inherited and you must be a family
member (or adopted family member) and also be the highest ranking
student and leader of the style or ryu (school/dojo). **note:
adopted does not mean legal adoption via the court system. In this
case in means having been made a member of the family of the
founder/current head instructor. The art is passed down to you and
by doing so you are a member of the family with a much tighter bond
than even by blood.**