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Schedulingaka: ESaka: EFaka: early dates

Early Start / Early Finish

In Plain English

The earliest possible dates an activity can start and finish based on when all prior tasks are done.

Definition

Early Start (ES) and Early Finish (EF) are forward-pass CPM calculations that determine the earliest possible date an activity can begin and the earliest possible date it can be completed, given its predecessors and durations. ES is calculated as the maximum EF of all predecessors plus any lag. EF equals ES plus duration minus one. These dates define the boundaries within which work can be scheduled without delaying successors.

Why It Matters in Bidding

Early Start and Early Finish from the forward pass establish how soon work can begin and finish, which lets estimators sequence trades, time material procurement, and plan cash flow against the schedule submitted with the bid. Knowing the early dates also reveals which activities have float versus those on the critical path, informing where to commit resources and where schedule risk truly lives.

Example

After building the bid schedule, an estimator runs the forward pass and sees the electrical rough-in has an Early Start two weeks before the owner's required completion, giving the team float to absorb a possible material delivery delay.

Related Terms

Late Start / Late FinishFloatCritical Path Method (CPM)Predecessor

Frequently Asked Questions

The forward pass works left to right: an activity's Early Start equals the latest Early Finish among its predecessors plus any lag, and its Early Finish equals Early Start plus duration minus one work day. The first activity starts on day one, and the chain propagates forward through every successor in the network.
Early dates let estimators verify the proposed schedule meets the owner's milestones, sequence subcontractor mobilization, and time long-lead procurement. They also expose float, showing where slack exists to absorb risk. A schedule that cannot achieve the required completion from its early dates signals the bid duration or logic needs revisiting.
Activities where the early dates equal the late dates have zero float and form the critical path that controls the project finish. Comparing Early Start and Early Finish against the backward-pass late dates identifies that path, telling the team which activities cannot slip without delaying the whole job.

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