I don’t understand what you mean here, why would “before dawn of the 3rd” become 00:00-08:00 of the 2nd?

I’m saying to shift what 00:00 is, to align with dawn(ish), so that a calendar day is comprised of a contiguous day followed by a contiguous night, which is how we typically intuit about days anyways when we aren’t talking about time.

I know there are practically modern issues with this, but this is a silly post about how unsatisfying it is for the day to start at midnight