Actually PHB did it the "smart" way. Dilbert's version documents non-performance and builds it into schedule. And it unfortunately leaves a "paper trail" that allows finger pointing afterwards. PHB's method acknowledges the week delay, but keeps it in the "undocumented" category.
Only the Secretary knows the REAL truth! (Don't they all?)
how to build a time line :
-estimate time needed for each task
-multiply by 2 each duration if common people are implied
-multiply by 3 or 4 each duration for task involving managers
-asume u'll be 1 or 2 month late whatever, because just letting people know the schedule will enhance delai.