These are pre-corvid solutions. Now? Different story because of the various new requirements by immigration. I'd research the situation carefully before going ahead with this - which doesn't include fb comments!
Interesting point you make about when the 72 hour count actually starts. You say it's the time stamp printed on your report - when the report was issued. Is this correct? If I was making the rules I would stipulate that the count starts when the swabs were taken. This is also printed on the test result. These two pics were taken from my recent test. You can see "collection time" as 8.00, and the report sign off time of 16.18 on the same day. Count finish time would be the advertised flight departure time.