Answer:
100 feet (in terms of distance)
Step-by-step explanation:
First you look around to check the flow of traffic around you on the rear, sides and front.
You then look for a little gap of 4 to 5 seconds in traffic before activating your turn signal.
You do all these at a distance of at least 100 feet before you make the lane change).
Check your mirrors (rear-view then your side mirrors).