Flaps are set on or before taxi at most airlines and many 135s.

You did your performance calculations to find your t/o weight, flap and trim setting.

You perform a checklist as you are crossing the threshold.

As you push the levers forward, you get a warning if the configuration isn't right.


Point is, you have about 6 points between push and takeoff roll where you check to make sure this doesn't happen.