When is the story set given clarisse's comment that "long ago firemen put fires out instead of going to start them"? On page 8

The story is set in a dystopian future where buildings are no longer made of wood or flammable substances. Firemen just burn books.

Clarisse is asking Montag about a time which he has never thought about. He has only thought about being a fireman who sets fires, and because he has never done any reading, he knows little about the past. The setting of the story in term of the time and place is simply in an American city in the future, a dystopian future at that. It is a future in which the world seems turned upside down compared to the time in which we live. Montag cannot imagine any other world than the one he was raised in.