When does one become "elderly?"

[emmaverybo]

39. Kept trying to get mother at 90 to have "someone in" just a few days a week I'd tell her. She

would say archly, “don’t you think it’s a bit premature?”
For Gawd’s sake I cried out one night, “You are NINETY years old.”
She pursed her lips cutely and looked down her nose at me, “You’re getting rather long in the tooth yourself,” she said.
God, I miss her.
Now SHE was elderly. Me, I’m just getting a bit long in the tooth.