Most places have a "morning rush hour", when many people are going to work from home,
and an "afternoon rush hour", when many people are going home from work.
You cannot use it in US-English at all. You can say "it's time to go home" or "it's quitting time" or, if you are a construction worker (they typically start work early), "it's beer-thirty" meaning 4:30 pm.
I will let the British-English people answer for themselves.
Afternoon rush hour and evening rush hour are both used in the U.S. It depends on factors like the person speaking, the location, the time of year and the amount of daylight as to which one is chosen.