The karate grand master.

[AnonymousOne]

Bruce Lee started training at age 14 and dazzled the martial arts world at age 23 - 9 years training

Ankichi Aragaki was considered at master at age 28. Training years not know off hand

Mike Tyson started boxing at age 14 and was world heavy weight champ at age 20 - 6 years training

Mohumed Ali became heavy weight champ after 10 years of training.

Its seems with the right training, you can become outstanding between 6 and 20 years

[kenpo_fighter]

the term "grand master" should be appointed to you by your superiors, not self appointed.

[Menjo]

I think the term grand master, should only be reconized with yourself when those around you see you as one. Even then putting those words behind will let you travel even farther in your training.

[Bleeding Lion]

i am a grandmaster in Okinawan Goju Ryu Bleeding Lion Style. Im going for my 10th dan in a few weeks...make that my 12th dan, why wait?

[Sam]

to be expert it is generally considered you must have been actively using your knowledge for 10 years

[unknownstyle]

seems like it huh, well they would have to create a new system so i dont think sometimes that they have real bearing to become a grandmaster, but some do