It says in the directions, approximately 2-5 minutes or when the popping greatly slows down.
Until (almost) all kernels have popped.
Try putting the popcorn in for four minutes. Listen and when the popping starts to slow down, take it out of the microwave. If it begins to smell burnt take it out right away.
until most of the popcorn kernels are popped.
It takes 2-3 minutes to pop popcorn (microwave).
in the microwave about a few minutes check it out on all about popcorn.org