When I read the website then I understand as described 72h start at end of arrival date, that makes effectively 3 full days plus arrival day.
“The confirmed seat onward ticket and valid visa to a third country or region (if required) are needed for entry. Based on the latest information, the 72 hours starts from 00:00 the day following the entry date in all the airports. For example, if an air passenger arrives in Guangzhou at 08:00 on June 2nd, then the latest time for him to leave is 23:59 on June 5. In this case, the actual stopover time is more than 72 hours. However, to play on the safe side, passengers are recommended to be more conservative and not to exceed the "strict 72 hours" which counts from the flights' scheduled arrival time to the departure time” [http://www.travelchinaguide.com/embassy/visa/free-72hour]
If so - I would rather fly as proposed below.
Meaning arriving on Mon , leaving in the night of Thu.
Could this please be checked with immigration?