The optimal time would be as soon as you can eat again, which is at 1/2 the food timer when it starts to blink.
Obviously, you will go through food faster staying as full as possible, but for optimal health/stamina stats, that is it.
The drawback is that you will go though your food stores faster and you will need to carry more food with you.
If you are in a multiplayer setting,and you are drawing from communal food stores, etiquette will vary depending on the other player's eating habits and available shared food supplies.

While at base and building/farming/chilling, some like to run hungry and have health/stamina pots on them to drink fast in case of an event/attack. (same with sailing)
I don't like to die from fall damage while building so I keep pretty well fed even at home. that said, I don't usually eat to stay as full as possible in those settings. Just while out in the harsh wilderness exploration/ boss fight/ dungeon situations.