[JRutledge]

You can wait up until the last minute. All the infield fly rule does is help the runners, but they still have to tag up and if the ball is caught they must go back. Even if the ball is dropped, the runners do not have to tag up and can advance as normal. So on a windy day, use your best judgement. But do not be in a hurry to call it in those situations especially. You might get an argument on your hands.

Peace