Before DS went to nursery it was 5-5:30 but often found he was too tired to eat, so we pulled it forwards to meet nursery time (4:30). It's only been in the last 4 months or so that we've started letting it go a bit later (5-5:30 latest) but we don't eat as a family - I tend to cook later and eat after he's in bed (7pm) as he's a notoriously fussy eater since around 2 years and the experience was just painful 
I tend to give him a big meal at lunchtime (12-1ish) and a smaller tea (sandwiches, scrambled egg etc) which seems to work better (in that he eats more that way).
He doesn't often complain of being hungry so seems to work for us. I am looking forward to the day we can eat together again though 