How does the introduction in Fahrenheit 451 go against conventional wisdom and signal to the reader that a different value system will be introduced?

Are you referring to the opening of the novel? If so, from
the very first line, the reader is aware that something is amiss. It opens with the
line, "It was a pleasure to burn" -- and then soon after, the reader finds out that this
is a fireman talking. He is burning something and then returning to
the firehouse. This is backwards from how things are supposed to be because a  fireman
typically gets a signal and then goes to the fire,
from the firehouse. Plus, Montag meets his neighbor, Clarisse, and
she guesses he is a fireman because he smells like kerosene. A fireman would
not smell like kerosene unless he was the one
doing the burning, which, in this case, is true. As the story progresses, the reader
soon realizes that the fireman is not putting out the fire, but starting the fire. A
very different world is about to unfold, a scary world.