When did Kakashi become a teacher in Class 7?

Kakashi became a teacher in Class 7 at the age of 22. When Kakashi was twenty-two, Sarutobi Hiruzen arranged for him to teach Sasuke Uchiha and Naruto Uzumaki and the seventh class that should be formed during the Spring Festival, so Kakashi became the seventh class teacher at the age of twenty-two.

Hatake Kakashi is the elite of Muyeyin Village in the country of fire. He is the fourth generation disciple of Namikaze Minato, the captain of Class Seven, and also the teacher of Naruto Usagi, Sasuke Uchiha and Haruno Sakura.

The power of Kakashi students

Haruno Sakura seems to be the only one who can successfully graduate under Kakashi, while Haruno Sakura also formed a team with Yamanaka Ino and Akimichi Chōji and graduated from endurance test in Shayin Village. As the two pillars of Konoha Ninja Village, Sasuke Uchiha and Naruto Usagi are all under the same name from beginning to end, which is why everyone says not to provoke Konoha easily.