There is a habit with many drivers on our roads to indicate late in regards to lane changing in particular. On any day you can see a vehicle moving to change a lane but the indicator is not activated until the sideways movement  has begun. If you think about it, the driver is indicating what you can already witness and therefore when the indicator is activated they are not telling you something you don’t already know. This is not the purpose of the indicator.
The indicator is designed to indicate your intention before you have started your maneuver, so the other drivers on the road  within your near vicinity have the opportunity to be aware of your intentions before you do it and thereby make adjustments to their driving if required.
It only takes 2 or 3 flashes of the indicator for the other drivers to be aware of your intentions and then make any adjustments required to their own driving.
This practice will, in turn, foster a greater calmness on our roads, which will then reduce the fatigue level we can sometimes unwittingly endure, always on the lookout for vehicles starting maneuvers before indicating. This may all seem pretty trivial to some but all of these small trivial issues all add up to become a  fairly stressful over time.
So try to foster a habit where you are indicating 2 to 3 flashes of the indicator before maneuvering.