Sometimes it is better for Drivers to leave later and to be on the road for a shorter time, sometimes it is just better to leave as early as possible. This option allows you to change the approach to the management of your Driver's time.
If you prefer a Fixed Start Time, do NOT tick this option and the Route Planner will force the Driver to start as early as possible. This leads to routes that, on average, are completed earlier.
This default mode comes in handy in those scenarios where it is important to finish a route early or for example when a Driver is paid from 8 o'clock no matter what.
If you tick the Flexible Start Time option, the Route Planner will postpone the actual departure time if that helps minimize the Driver's Total Working Time.
Let us repeat that with Working Time we mean the total time between the moment Drivers leave and hit the road towards their first stop and the moment they finish their route (comprising idle time, drive time, service time, break time and return to their initial position if in round-trip mode).
For this reason, the Route Planner may see it fitting to have Drivers leave later than the beginning of their set working time window, whenever leaving early does not contribute to a shorter Total Working Time. For example, because of some Time Windows' settings, Drivers would have to wait before serving certain Orders and this would generate idle time and decrease efficiency.
Please note that like all other Driver Settings, Flexible/Fixed Start Time can be assigned/modified from under the tab My Fleet or from under the tab Route Plans (by clicking on the Driver's name in the lower part of the screen).
Remember that if you change a Driver’s settings from the tab My Fleet, the new settings will be applied to all future Route Plans whenever this Driver is utilized. If you only need to modify settings only for a specific Route Plan, you need to do it from the tab Route Plans.