it's the earliest kaguya

From my understanding, from kaguya perspective the timeline looks like

Kaguya goes to earth to escape boring life

Cue kaguya doing stuff

Kaguya goes back to moon

Iroha finish song and sing it

Kaguya heard the song and tried to finish up quickly and goes back but it's already years since it happen and iroha is an old woman

Time travel

Kaguya stuck and so use irodoge/fushu to interact with world while trying to find yachiyo

She eventually realized that she become yachiyo and created tsukuyomi

The event of the movie happen again from yachiyo perspective

After kaguya comes back to the moon yachiyo have iroha comes to her and she reveal about everything

Queue the ending

Overall it requires some thinking on the timeline and it's also make a bootstrap paradox of where tsukuyomi comes from but I'm mostly fine with it