'You made good time'

I actually liked & kind of understood why tey had Temple say that. I think it showed her improvement throughout the summer with her aunt, and showed her trying to be more "normal" (i hate using that word), even though she may not have understood exactly why people say that phrase, she still used it. I viewed it as being kind of the same as when she introduces herself & shakes peoples hands. It's not something that she really seems to want to do, but does because she knows that's what you're supposed to do. So I think that phrase was showing her progress in trying to fit in with normal society & also showed that the cattle squeeze box she used throughout the summer helped her out.

I think its apparent that her mother had taught her when to properly use figures of speech, we basically see her do it every time she introduces herself. She has been taught a routine to do when she first meets someone, and "you made good time" could very well have been something her mother taught her to say when someone had traveled to see her.

Autistic people tend to mimic, so it may be an expression she heard people use a lot, so she picked it up. Especially if someone explained its meaning and she could adjust how she visualized it.

I'm a little late, but if you watch closely in this scene, you can see Temple's aunt give her a nod right before she says that. I think we are to assume that her aunt had been working on her social skills with her and "coached" her to say that when her mother arrived.