Board Thread:Naruto Discussions/@comment-45851667-20200520192705/@comment-32685487-20200522225247

No, it doesm't say that. But Shisui awakened his MS at about 6 and he knew all about how Koto worked and what it was called on Itachi's first mission to join the Anbu.. when Shisui used it on Mukai. Shisui had clearly used it before that mission.

https://naruto.fandom.com/wiki/User:Seelentau/Naruto_Timeline again everything is referenced here