I don't think it matters what other people do, in this country, other European countries or Inner Mongolia. Different lives and different routines, there is no superior time. As an aside I've been into too many fast food and chain restaurant joints in other European countries between 6 and 7 to find them stuffed with families ;)
Our family meal times have changed many times over the years depending on how our days are structured.
What is your husband aiming for? What time would he like to eat? Is he happy with a set time or is he expecting it to be fluid everyday to fit in with him? Or somewhere in between?
If 6.30 is a better time then maybe you could do something like sit the kids down at 6.15 to give them a starter of carrot sticks, salad, or corn on the cob type bits. Whilst getting the rest ready. In this house there is always a big bowl of chopped salad on the go in the fridge. My teens come in starving and they get pointed in the right direction.
He could always eat and then go back to work? I often used to do this when I worked at home. I would prep food, work, feed us, go back and finish a report or fire off some emails for the next morning.
If he's expecting everyone to hang around waiting for him to finish at 8pm he's just going to have to put up with eating alone, if everyone else is hungry earlier.