Board Thread:Naruto Discussions/@comment-3279282-20140828133937/@comment-24519434-20140829021055

Kakashi and Zabuza are both 26 in Part 1. Zabuza was 9 when he graduated the academy under Yagura's rule. Kakashi had made Jonin by the time he killed Rin, he graduated the academy at 6, he didn't make Jonin before Zabuza turned 9. It was after Yagura's reign that he Rin became a Jinchūriki.