With a declared Intention of safeguarding the existence of state of Pakistan and its borders, China will do whatever it takes to do just that. And Pakistan today is facing an existential threat due to the Indian launched "Water War" that jeopardizes the very existence of its population and hence the state of Pakistan.
Having said that, China is also fully aware that any escalation due to induction of a 5th Gen platform in the region will create problems for it. It will leverage Pakistan to counterbalance India as much as it can but will not go overboard to induce induction of more sophisticated weaponry that can be used against it in the region if it can be helped.
A 5th Gen platform in the region will pull in active US meddling spurred by the usual antics of our Indian friends across the border and its larger diaspora across USA.
Therefore, in my opinion a more prudent approach would be to familiarize, train, and build capacity and eco system to absorb J-35 on the slow route (This gives time for certain J-35 systems including man-machine-sensor fusion to mature) and induct it in a fully capable 5th Gen eco system state as an when required. I also think the trigger point would be for IAF to decide on SU-57 or its derivative. Meanwhile, the other subsystems in the overall eco system that supports the J-35 will be put in place. The last piece would be the jet itself once the green light on SU-57 is given. Another possibility would be the absolute failure of convincing the Indians to resume the IWT in its original form.
My take on the induction timeline.
This makes a lot of sense. Just my thoughts here are that China actually thinks about India much less then people imagine. They no longer see it as a threat, the main vision they see India through is as a market of 1.4 Billion people, China wants this market on it's own terms.
Pakistan is no longer seen as just a balance to India anymore, we are a physical, diplomatic and military way for China to expand it;'s influence westward. Pakistan itself is cocking that up a lot on the economic front with delays on CPEC projects, mismanagement and bad Balouch security situation. On the military and diplomatic front we have played a blinder and China is involved.
Chinese backing for Pak mediation efforts and Pak introduction of advanced Chinese systems in GCC for the first time (yes, I know GCC has some Chinese stuff already but am talking Fighter jets and SAMs).
In this light, J-35 in PAF service helps China is several ways
1) Balances India, or even to an extent makes IAF lagging behind PAF for first time ever
2) Shows world a first class air force has inducted Chinese 5th gen, and possibly provides another testing area if we go to war again
3) Opens up Mid East to Chinese kit. Like we did with J-10 expect to see J-35 exercise with close Pak allies like Qatar and Saudi who will see J-35 close up, now also remember we train A LOT of Qatari and Saudi cadets at Risalpur and we have quite a few people on deputation or as contractors in both