This came up in my TL and made me realize I'm super obsessive with this when I write kidfics. I'll go by memory, thinking about kids in my life, but then I'll read articles and forums to make sure I'm not saying something stupid 😅
I've slowly had to phase out reading kidfics because I'm getting pickier and pickier about the characterization and realistic developmental milestones*
*developmental milestones = not having a six year old speak in baby talk or a three year old spill the secrets of the universe