There is a reason that Graf Zeppelin never got finished. They didnt have the resources as German naval construction was never a priority (20,000 naval construction workers were conscripted into the Wehrmacht for Barbarossa). Hitler was simply never sea-minded. And the Navy didn't have an equivalent of Goering in the Senior Nazi elite.
It's also worth remembering that Germany wasn't put on a full war-production footing until it was far too late (Hitler apparently didn't want the German people's living standards to fall); probably their single biggest mistake away from the battlefield (their aircraft industry didn't reach full production capacity until 1944)
Germany always planned on the assumption that WW2 doesn't break out until 1944 (they never dreamed that Britain and France would go to war over Poland).
It was suggested that Graf Zep accompany Bismarck (this has come up on a regular basis since the war). Basically, in Spring 1941, either Bismarck is ready for sea or Graf Zeppelin, but not both, unless there is a major change in priorities within the German command structure. Which, ironically, is the only way the Germans have a chance of winning the war.
Also, if the Germans complete and commission Graf Zep, they still have to get it out of the North Sea, even if they are prepared to risk it (Bismarck basically got lucky). I don't think Tirpitz ever got into the Atlantic! Plus the British would have tried even harder to sink the Graf Zep then they did the Tirpitz.
Finally, it should be mentioned that naval experts have said that the Graf Zep was really badly designed (can't remember the details, but they should be on the naval websites)