1. Start with the date the item must be on site
Use the required installation date, not the date work begins in the room. If the date is not yet reliable, resolve that dependency before treating the calculation as a commitment.
2. Confirm the current supplier lead time
Ask whether the quoted lead time begins at approval, deposit, order release or another event. The workbook uses calendar days and cannot verify supplier availability.
3. Add the time needed for approval
Include the days your client or team needs for review, revision, payment and order release. This is your planning buffer, not a universal recommendation.
4. Review the latest approval date
The sheet subtracts supplier lead days and your approval buffer from the required install date. More than seven days is MONITOR; four to seven days is DUE THIS WEEK; zero to three days is APPROVE NOW; a passed date is LATE: ESCALATE.
5. Reconfirm after a late approval
An approval after the calculated deadline is not automatically a failed installation. It means the old assumption is no longer enough: confirm current delivery before promising the install date.
What the result does not prove
The workbook does not model business days, deposits, shipping interruptions, fabrication slots, purchase orders, change orders or field conditions. Supplier confirmation and the actual project schedule remain authoritative.