Final answer:
You should give the proper signal at least 30 meters or 100 feet before turning left to ensure safety and provide other road users time to react.
Step-by-step explanation:
When turning left, it is crucial to give the proper signal well before you make the turn. Although the exact distance can vary by jurisdiction, a good rule of thumb is to signal at least 30 meters or about 100 feet before you turn. This allows other drivers and pedestrians adequate time to anticipate your actions and react accordingly, ensuring safety on the roads.