144-hr visa free - Travel would be Vancouver - Shanghai - Seoul - San Francisco

My employer is flying in to Shanghai on the 26th, and from everything I can find online the 144-hours starts on the 27th at 00:01. So his 144th hour would be on the 3rd, is that correct? Once he is in the airport for departure, does the 144-hour rule end and now he just waits for his plane? Sorry for all these stupid questions. We ran into issues with getting an actual visa (no pages in his passport, no time for renewal) and then found this option!