Sometimes the work starts already on the last cruise before drydock, this could include having certain areas of the ship unavailable plus all kinds of noise and dirt. If Quantum is not doing a revenue cruise to Singapore, it probably would not cause such problems on the 10/1 Cruise. I had a TA cancelled on Mariner, was supposed to go from Barcelona to Miami,then dry dock, we were on board from Dubai to Barcelona. Good thing it cancelled many months ahead of time, about 1,000 of us got off in Barcelona and two days later got on the Carnival Horizon headed to NYC . Was on a cruise with NCL on which they started doing all kinds of work including replacing carpeting on our deck, lots of people including my wife developed terrible coughs. The workers wore masks, none available for us folks. This was prepandemic.
Always a good idea to see where the ship has been and where it is headed for this reason.