It's really the domestic China leg between two international legs that's the problem. The PLA can close domestic airspace at anytime without warning or reason. Had the OPs destination been SZX probably would have been ok but even then the possibility of being late there.
I flew from CAN to HGH which is a two hour flight. That flight was delayed 5 hours. Had I flew the day that I needed to get there, I'd miss my meeting. Even flying the day before, there's a possibility albeit less. Think the message is don't fly domestically in China without lots of margin.