Currently the test requirement window is by calendar day, not a 24 hour clock. A test three days prior in the AM is still OK for an afternoon / evening flight, this will likely be the same for the 1 day prior requirement
That's why I said - "the day before flight". Sure, you can get tested at 8am Friday and that gives you 30 hours til your 2pm Saturday flight. If the testing facility is spot on with it's 24 hour response you are fine, although many would be sweating and nervous until it arrives. That's also why I said they might have to fall back onto a rapid test. Test at 8am Friday, if you don't have results by 10-11am Saturday it might be wise to take a rapid test. Even under current requirements I wouldn't want to be headed to the airport with my bags in the hope an email (with negative result) will arrive before I reach the counter.