In this single iteration, the crew's start time is 247 days.
However, during pre-construction planning, one can only
estimate this start date. Given the uncertainty in getting
matching spools to site, it may make sense to build in a time
buffer or lag preceding the Install activity to enable the crew to
be optimally productive once they mobilize (e.g., start Install no
earlier than day 250). Buffering protects the installation crew
from upstream process uncertainties and buys time for them to
plan and get ready, or do other work in the mean time.