[ElProximo]

I always understood anything after 6pm was properly 'evening' until midnight where it is properly morning until 12 noon which is afternoon.

Now that you mention it... ..I don't recall seeing any actual proper guidelines, scholarly reference, council or legal decisions for that.

I suppose, on Saturday 'morning' at 1:04 am we are still up saying its 'Friday Evening' and 'Friday night'.
In Winter, I agree at 4:50 and its nearly pitch black and cold and you wouldn't say to someone 'good afternoon'.

There must be some official rulings on this. Where. Roget's?