Officially, when does the afternoon end and the evening begin? Was discussing it with a friend the other day and I said to me afternoon ends at 18.00 and eve begins
The Oxford English Dictionary defines 'afternoon' as the period from noon to evening. It then defines 'evening' as the time at which 'dusk' takes place...ie roughly at sunset. It would seem, therefore, that the start of evening is - strictly speaking - moveable! However, given that the sun sets very late in summer, that would suggest that summer evenings don't even start until about 10 pm in Scotland! As a rough guide, I'm sure your 6 pm idea is pretty generally acceptable.
Many years ago I did a stint as a telephonist and "good morning" was from midnight to noon followed by "Good afternoon" until 6 and then "Good evening" - "good night" having a different meaning altogether!