Top 9 in Top 12 Code of Conduct on Vietnamese dining tables.
Waiting for another person to sit on the dining table before hitting the chopsticks is a minimum courtesy. You should do this, not just outside of society but for both family member people. Let's wait for everyone to freeze and then start making meals.
When you do, you do not have to eat food before the landlord or the feast. This only happens except if you are offered a pre-proposal because otherwise you will be rated as taking a meal and not respecting others.