90 chapters
If no off panel during fights and counting the chapters between Acts.
IMO Kaido and Mama will be defeated around the end of 2021.
We need to finish Oden's flashback. See Luffy and co's surprise attack fail, find the traitor, a little backstory on Kaido. This alone is gonna be at least 20 chapters long (end of Act 3).
Then there's the real war against the Beast Mom Pirates and taking down Orochi. With the Numbers, Tobi roppo, Calamities, the BMP, Orochi gang... There will be fights. And since Luffy's fight will surely be longer than the fight against Katakuri. If there is no off-panel this war will last at least 40 chapters (Act 4).
And once they're defeated. There'll be at least another ten chapters to conclude the arc (Act 5).
Chapter 1060 and Wano is obviously over. It will end between February and May 2022.