Til the USN came to town. Then the GZ would have been talking to the fishes.
The KM had zero experience operating CVs. Zero. Had the GZ been finished, there is no reason to expect it would have been early in the war, otherwise, well, it would have been finished. Had they not done so when they were winning everywhere, you must assume she'd be commissioned after things went south. Think 1942 (late) earliest.
1943 is a bad time for "on the job training" in CV operations vs the USN.
Also, the KM had already picked navalized 109s and Ju-87s as the planes. Noobs. Water-cooled engines? WTF were they thinking? (yeah, I know about navalized Spits, they were stupid, too. You want planes that can come home with cylinders missing when the alternative is being shark food.
Another problem is that they followed the RN/IJN model for plane embarkation. The GZ was designed to stow her aircraft below. That might be OK from a weather standpoint in the North Atlantic, but it makes for slow turn around times, and dangerous CVs. It was gassing and bombing up planes below decks that caused the IJN disaster that was Midway (contrary to popular myth, there were not many planes on the IJN flight decks that day, they were warming up in the hanger spaces). USN doctrine was to embark all aircraft on the flight deck. They only went below to be worked on. This allowed USN CVs to carry considerably more aircraft.
Quantity has a quality all its own
