Pretty sure the goal is to turn in at the point that is required to hit the apex and maintain the maximum amount of corner speed.
If you have to scrub speed in order to make the corner, you should brake and then turn in rather than scrubbing the speed through understeer, no?
I don't think that you will wait to turn in with a car that has oversteer. You will either tame the oversteer by maintaining the correct entry/corner/exit speed, or you will use it to your advantage to bring the car around.