It's done before fly-down time to allow you to locate and set up on a bird. It's done after fly-up time, when gobblers are settled on tree limbs, and to hatch a plan for the morning. I've done it before dawn, at dawn, at dusk, and after dusk . . . even an hour or so after dark with some success. I've done it and called in owls. I've done it and heard silence.