'“The earliest date that a task could possibly start, based upon dates from its predecessors or successors, other constraints and any leveling delay.
'SOURCE; microsoft project glossary-projectlearning.net
In the critical path method, the earliest possible date on which the uncompleted portions of an activity (or the project) can start based on the network logic and any schedule constraints. Early start dates can change as the project progresses and changes are made to the project plan.
The Early Start date is defined as the earliest calculated date on which an activity can begin. It is dependent on when all predecessor activities finish. Most PM software calculates early dates with a forward pass from the beginning of the project to the end.