the last wedding i went to started at 12 and we were gone by 5pm

a friends wedding was at 4pm (well, 4.30, but on invitation was 4 so no one was late!) and i think we left around 10pm.

i dont think it matters what time it finishes, as long as guests have warning, rather than 'this is the last song' then they flick the lights on kinda thing!