The longer you wait to harvest your hot peppers, the hotter they’ll be. You can pick some before they’re fully ripe, but they won’t have the same heat as fully ripened peppers. It’s your choice.
When you do go to pick your perfect hot pepper, don’t just yank it off the plant; that may damage the plant and could jeopardize future ripe fruit. Use a knife or garden scissors to make a clean cut, separating the stem of the fruit from the plant.
If you have frost in the forecast and your pepper plants are in the ground or in raised beds, pick any peppers that look remotely ripe, then protect the remaining plants with a row cover. Row covers can increase the heat around your plants and protect them until the temperature drops below 25 degrees F; then growing season is definitely over.
Unwashed hot peppers will stay fresh in the fridge for a couple of weeks if you keep them in the crisper drawer. But it’s best to start using some of your harvest fresh and then plan to preserve the rest.