HKSM

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?

1. B must start 3 days after A finishes.
2. B can start 3 days before A finishes.
3. B must finish 3 days before A starts.
4. 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.