When you must travel down a hill, when should you switch into a lower gear?

Question

You should always slow down and shift into a lower gear before starting down a hill. If you do not begin to drive down a hill at a low enough speed, you risk overusing your brakes, causing them to overheat and fade.

Accepted Answer

Before you start going downhill

Answer

As you begin to move downward

Answer

As you go downhill and pick up speed