If everyone is hungry at 5:30, why not have dinner then? Unless you can’t have it ready because of other commitments.
My DH doesn’t come home until after 7:30; by then, I’ve been ‘snacking’ for hours because I’m starving.

5:30 is a perfectly normal time to eat

I prefer dinner on the early side. Kids eat lunch at school quite early. They have a snack right after school. Dinner at 5:30-6 makes the most sense. If they feel peckish again just before bed at 8 they may snack on fruit, nuts, yogurt, cheese etc.