When is the earliest date to take a PCR test for a midnight flight on May 3, and when should I receive the results?

Your results must be within 72 hours of departure.

Thailand has for some reason results 72 before flight but some airlines/transit places dont accept so just do test 72 hours before your flight results dont take long

72 hours before departure. I would contact your airline to see what they will accept in this instance.

I never seen in less than three days

It’s always no less than three days right