First KJ-600 mockup was spotted at the same place around January 2017, no? Then the actual prototype first broke cover with an image in august 2020.
Assuming this latest image is recently taken and assuming there's going to be same/similar period of introduction, (which is a huge assumption on so many levels) we might (or might not) see the first J-XY image 43 months from now. Meaning around January 2025.
Of course, I don't really think that's necessarily going to be true. We might see it much earlier. It's just something to think about.
What is important here is that J-31(?) has the PLANAF seal of approval. I wonder if it will receive the PLAAF seal of approval next.