Eh I'd say pretty soon after Big Mom's tea party, like bomb goes off in face -> Luffy brought up -> Jinbei stands up for him -> shits about to go down and boom KHA crash the party and give Jinbei a chance to get out of dodge. Since his association with BM will basically be null and void he'll join up with the SH's.
So say Dressrosa goes another 20-30 chapters, then we have the fallout for 5-10 chapters, then we switch to tea party and those events go for 5-10 chapters and then I dunno you'd expect a gap before Jinbei got back to them, probably in the middle of the next arc, so say 20+ chapters. So I'm guesstimating about 50-70 chapters away, but with a very crude form of estimation.
All seems alittle too sudden, but I can't shake this feeling that everything wont go just as they planned , I can totally see Luffy deciding on a detour if it meant helping out Jinbe one way or the other. There is also Kid's alliance to consider , we don't know which Yonko they're after and they could just as easily fall on Big Mom's side of these, factoring in what we heard from Tamago and Pekoms on FI. I wonder how Jinbe will figure into all of that.
~100 chapters at best, ~150 at worst, from now on.
So somewhere between 3 years and 4 and a half years.
I'm assuming Wano is coming right after Dressrosa. Jinbe wouldn't feel out of place there, but Wano seems to be Kaidou's territory.
This sounds more Oda-style, lol
Wano just seems so up the Blue Fella's alley, and i'd love to see some Kinemon-Momo-Jinbe interactions , but yep, it all comes back to how soon they go after Kaidou.