I swear, I'm beginning to understand why my blogging friends eschew the NaBloPoMo prompts: the grammar alone may do me in. "At what moment does one leave childhood, and enter adulthood?" Does that work better?
Is it when one corrects strangers' grammar? In that case, I've been an adult since I was five.
My first response to the question, however it is worded, is: "If it ever happens, I'll let you know."