HKSM
Lead
A time offset that allows a successor activity to begin (or finish) earlier than its predecessor would normally permit; it is the amount of time the successor is pulled forward relative to the predecessor.
Key Points
- Often implemented as a negative lag in scheduling tools (e.g., FS - 2d), creating overlap between activities.
- Can shorten the overall schedule by enabling parallel work, but may raise risk or rework if used excessively.
- Should be logically justified and documented; do not use leads to mask schedule problems.
- Applies to any dependency type (FS, SS, FF, SF), with FS plus lead being the most common case.
Example
Development and System Testing have a finish-to-start relationship. By applying a 2-day lead, Testing begins 2 days before Development is fully complete, allowing overlap and earlier feedback.
PMP Example Question
Activity B has a finish-to-start dependency on Activity A with a lead of 3 days. What does this indicate?
- B must start 3 days after A finishes.
- B can start 3 days before A finishes.
- B must finish 3 days before A starts.
- A can start 3 days earlier than planned.
Correct Answer: B — The successor starts 3 days earlier than the predecessor finishes.
Explanation: A lead advances the successor relative to the predecessor. With FS and a 3-day lead, B begins 3 days before A's finish.
