Hi,
Judging from ULTRA signals, the
Flugzeugbestand und Bewegungsmeldungen were sent within a day or two of the end of the relevant month. An example: even in late-November and early December 1942 in Tunisia when things were very hectic, II./J.G. 51 and III./Z.G. 2 sent their F & B for November to the II.
Fliegerkorps Quartermaster on the evening of 30 November, and II./J.G. 2 did so on 1 December. So only losses from the correct months would have been included.
Cheers,
Andrew A.
Air War Publications -
www.airwarpublications.com