For those of you who are getting confused considering it’s been 2 years or so in real world time since the start of the time-skip in One Piece, here is a timeline for the new world up until Zou to make things make more sense.
From this timeline we can deduce that the reason for Jack to release the deadly poison gas on Zou could be due to receiving news in regards to the capture of Caesar Clown.
Also, Strawhats reformed and defeated Doflamingo and made enemies with Big Mom Pirates in like 2 weeks.
That’s just crazy!