To change lanes safely, it is important to follow certain steps. First, you must turn on the **direction indicator light** to notify other drivers of your intention to change lanes. This light is yellow and blinks to be visible. It is crucial to turn off this light once you have completed the lane change, as its function is to indicate the movement you are making.

Additionally, when changing lanes, you must ensure to do so with sufficient distance from other vehicles and without sudden movements. It is important not to interfere with vehicles already in the lane you are moving to, as they have the right of way.

Therefore, the indicator light should be turned off **when you have already changed lanes**, as its purpose is to inform others of your intention to move, not your current position.