Is that true? I'm taking most of my building dates from M.J. Whitley's books. According to him in German Capital Ships of World War Two:
-her hull was ordered on 11th February 1935;
-her machinery was ordered on 16th November 1935, and:
-she was laid down on 30th September 1936, 4 months before Graff Zeppelin. At that time her projected completion date was November 1939.
According to Whitley her yard number was 555 and Prinz Eugen's was 564.
Conway's doesn't have a laying down date for Aircraft Carrier B, only a question mark.
If that is true then it mucks my plans up somewhat, because I was going to have a 7,500 ton light cruiser (an enlarged Leipzig) laid down in place of Aircraft Carrier B. When Cruiser O was launched in September 1937 the berth was going to be occupied by another light cruiser or a Bismarck class battleship.
I don't have it handy but I would trust what Erich Gröner says as final. A number of authors use this work as their back source on such things. I have a spreadsheet of laydown dates and yards for the Germans that I made.
Die Deutschen Kriegsschiffe 1815-1945 Band 1: Panzerschiffe, Linienschiffe, Schlachschiffe, Flugzeugträger, Kreuzer, Kanonenboote by Erich Gröner
The above is available in English.
Few works give a solid date for Flugzeugträger B, I have seen a number given and the common element is 1938 and the yard. With her being on the same slipway as Prinz Eugen that suggests a laydown date of soonest being October 1938.
By the way I wouldn't have the Germans build any O class, this is one nickname applied the O Class recall they were to be ships O P & Q Ohne Panzer Quatsch "Without Armor Nonsense." They were a BAD design and heavy cruisers presented a gunnery threat to them.
Michael