Data Type Date (date field: A type of field whose content is a date. Examples include the Baseline Start and Early Finish fields.)
Entry Type Calculated (calculated field: A field in which the value is determined by Project based on information in other fields. Project may recalculate the value automatically or when you specify, depending on your choice of calculation settings.)
Description The Early Start field contains the earliest date that a task could possibly begin, based on the early start dates of predecessor (predecessor: A task that must start or finish before another task can start or finish.) and successor (successor: A task that cannot start or finish until another task starts or finishes.) tasks and other constraints (constraint: A restriction set on the start or finish date of a task. You can specify that a task must start on or finish no later than a particular date. Constraints can be flexible [not tied to a specific date] or inflexible [tied to a specific date].).
How Calculated When you first create a task, its early start date is the same as the scheduled start date. As you link the task to predecessors and successors and apply any other constraints, Project calculates the early start date as the earliest possible date this task could be started if all predecessor and successor tasks also start on their early start dates. These calculations are based on a fixed task duration. If there is a leveling delay on the task, this delay is also figured into the early start date.
Best Uses Add the Early Start field to a task view, along with the Early Finish, Late Start, and Late Finish fields, to analyze slack (slack: The amount of time that a task can slip before it affects another task or the project's finish date. Free slack is how much a task can slip before it delays another task. Total slack is how much a task can slip before it delays the project.) time in your schedule.
Example Several critical tasks are slipping and likely to cause the entire project to be severely delayed. You add the Early Start, Early Finish, Late Start, and Late Finish fields to the Task Sheet view in order to analyze the delays and find any available slack time.