I'm not sure how long it'll take timewise, because Oda's breaks, shonen jump breaks, etc are unpredictable.
But I think it'll be two volumes until the fighting is over and for the after-conflict celebrations to get wrapped up.
- About 4 chapters to wrap up Linlin.
- About 2 chapters to wrap up Yamato
- About 2 chapters to wrap up Cipher Pol on Onigashima
- About 1/1.5 chapters to wrap up Orochi Kurozumi
- About 5 or 6 chapters to wrap up Kaido.
- About 4 chapters to close out the arc / ending party.
A lot of these are gonna share space in the span of a single chapter too, but I imagine for any plotline to really end it'll consume the bulk of the chapter its in. So about 15/20 chapters left before Wano ends IMO.