Its your first attempt to produce F-22 class engine and you're still struggling for quality problem with your WS-10, you have
no vast experience to build descent high performance engine from scratch your first attempt is WS-10, second WS-13 which is still development phase, third WS-15, so when you predict that WS-15 will be fit on J-20
@Figaro
no vast experience to build descent high performance engine from scratch in the class of F-22's engine F-119, so its safe to assume that WS-15 takes little more time to be matured because this is their first attempt to develop F-119 class engine @Figaro