Final answer:
Signal and start to slow down at least 100 feet before the corner to ensure other drivers are aware of your turning intention and for you to safely reduce your speed.
Step-by-step explanation:
When approaching a corner where you intend to make a turn, it is important to signal your intentions and begin to slow down well in advance of the turn. While the exact distance may vary by jurisdiction, a common rule of thumb is to use your turn signal and start to slow down at least 100 feet from the corner. This action ensures that other drivers are aware of your intent to turn and gives you ample space to safely reduce your speed for the maneuver. Checking your rearview mirror before slowing down is also recommended to ensure the driver behind is aware that you are going to slow down and has time to adjust their speed accordingly.