To harvest peppers, hot or sweet, wait until they have turned colour and harvest by snipping the stem with a pair of garden shears or scissors. Did you know that there is no such thing as a green pepper? You can harvest them green if you prefer, but all peppers will change colour if you let them ripen.
Harvest eggplants the same way, once they have reached a desired size, and become slightly less hard, snip the stem.
Tomatoes ripen as when their colours change, they soften a bit to your touch and come off easily off the vine. Give them a taste and see how you prefer them. You can let them ripen on the window sill as long as do not have nicks are bruises.