That's exactly the point ... besides all brahoo, "Pakistan will get J-31 anytime soon"! there is simply no J-31 yet.
Even more so - and here agreeing again with
@_NOBODY_ - it depends on so much other factors: Will the PLAAF indeed go not the J-31-road, then who will pay for the J-31's development? Surely not SAC on its own, surely not China if not another customer is in the background and IMO unlikely Pakistan? So it will take even longer ...
As such, even if, then the most likely guess is, this alleged "new J-31" is not exactly the FC-31 no. 31003 (often erroneously called J-31) but a "J-35-light" including all the revised aerodynamics - aka the revised spine behind the canopy for improving aerodynamics - but without all carrier related things like the landing gear & catapult bar, the folding wings (maybe like the F-35A vs F-35C a smaller wing) and so on.
All this will take time ... at least several years so even if a "new J-31" prototype may be ready already this year, it will at least take a few years of flight testing, system integration, certification and so on ... in the end, surely 5-6 years a minimum, so that deliveries to Pakistan or any other customer can happen only by 2030! If this is "soon", then I can agree.