So, let's go through this...
Is an isekai ☑
Reincarnation as a baby with past knowledge ☑
Understanding of OP-level skills from a young age ☑
MC acting somewhat unfitting of their current age ☑ (but is called out on it, refreshingly)
Beating adults early on ☑
And now, academy arc ☑
Inb4 tournament arc, harem building, some sort of dramatic misunderstanding, befriending demon(s)/demon lord(s) ... anything else I'm missing? xd
This is still a fun read though