⏩ Lead Time
Lead is the amount of time that a successor activity can be advanced with respect to a predecessor activity.
🧩 Logic:
“Start the next task before the previous one fully finishes.”
📌 Example:
- Testing starts 2 days before development ends.
→ This is a lead of 2 days on a Finish-to-Start relationship.
✅ Use case:
- To overlap tasks and compress the schedule (fast-tracking).
🕒 Lag Time
Lag is the amount of time that must pass after the predecessor activity ends (or starts) before the successor can begin.
🧩 Logic:
“Wait some time before starting the next task.”
📌 Example:
- After pouring concrete, you need to wait 3 days before framing begins.
→ This is a lag of 3 days on a Finish-to-Start relationship.
✅ Use case:
- To model waiting times, curing periods, or buffer zones.
🧠 Summary Table:
| Term | Meaning | Example | Purpose |
|---|---|---|---|
| Lead | Successor starts early (before predecessor ends) | Start testing 2 days before dev ends | Schedule compression |
| Lag | Successor is delayed (after predecessor ends) | Wait 3 days after concrete pour before framing | Buffer / wait time |
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