When Should an Estimate be Completed?
As noted previously, there are different points in a project when an estimate should be prepared, reviewed, or revised. These include:
You must develop the WBS before preparing an estimate, even if it is only the preliminary version.
If you take over a project, you should prepare a new estimate or validate an existing estimate. Review staffing and skill levels stipulated in the project proposal and assumptions. Questions you should ask include: Are the skill levels correct? Are the hours assigned for tasks realistic? Do the hours include time for holidays, vacation, and any other downtime?
The estimate should also be reviewed or reworked if an assumption becomes invalid. Always document your assumptions as part of the estimate. This helps explain an incomplete set of data and also helps make your estimate more credible and complete.