Maya said that WS-15 will start flight testing on J-20 around 2016-2017. Mass production will begin in 2023-2025.
This is why I believe the Su-35 deal, China uses the 117S as the interim engine for J-20 from 2017-2022.
Then use WS-15.
Sorry... but I have to disagree. The sales of the Su-35 didn't spec the individual sales of the engines so I would assume that 2 engines for every 1 Su-35... and that sales is for 24 aircraft. So if the Chinese buy those aircraft, they would have to dismantle the engines from the Su-35, then store those Su-35 somewhere in the warehouse and use the dismantled engines for the J-20. This is true legit ways, because I don't recall a technology transfer or that the Chinese could start building their own 117S. However, if the Chinese started reverse engineer those 117S, then that is another matter altogether, which again will put themselves into more bad publicity (although the Chinese can really ignored that, but it is not a good image afterall). Secondly... unless the 117S design is specifically similar to what the J-20 had been designed around, then the Chinese would need a major redesign of the fuselage to allow the 117S to be put into. And again, unless the WS-15 is similar in dimensions, components, etc with the 117S, then the J-20 needed to go through another major redesign to be compatible with the WS-15.