Going strictly by the movies, Anakin was too old to begin training and looked about 8. The youngest initiates at the Jedi Temple looked more like 5, and out-of-movies info (google search) suggests that future Jedi are raised by the Jedi as soon as they are found, which might be soon after birth.
So if all Jedi are growing up together, in common surroundings, in one physical location, why do some of them have different accents? I understand they could be born all over the Galaxy, but 5 is definitely young enough to adapt to a completely new accent.
Dooku, Windu, Obi-Wan and Anakin all have different accents. (Though I realize why Anakin is a sub-par example)