Definition of "PCR test within 5 days of arrival"

Splitting hairs here, but what exactly does "PCR test within 5 days of arrival...." mean? I've also seen it stated as within 5 days of "travel". Example: We plan to arrive in the BVI on Thursday July 1st. Would a test taken the Saturday before be within that window? In other words, does your arrival day count as Day 5?
Thanks TTOL team. You all are the best.
Husker.

Travel day is day 0. For a Thursday arrival, you should test on Saturday or later.

As always, the man with the answers. Thank you, Jason!