I believe they are going to attack the moment China can or does not want to stop them anymore.
Considering China’s whole military has recently been shown to be stripped bare by corruption from the top to the bottom, China’s power in the world is shaken. They could pivot to letting DPRK off leash a little bit, as a threat to step aside and let DPRK do what they want with the nuclear weapons they absolutely have, now on missiles that can reach the west coast of the US.
Bunch of top brass got pulled out after some of the corruption was discovered. Like rockets fueled with water.