What time do you turn off your front light on Halloween to let trick-or-treaters know that you're done giving out candy?

Of course, we turn off the front light when all of the Halloween candy is gone, but some years we just don't get that many trick-or-treaters, so we have a lot of candy left over. But you have to have a cutoff point somewhere, even with lots of candy left. So if you still have lots of candy left, how do you decide when it's time to call it a night?