Herb, there were just a few J-Blocks Erfurts made. I don't recall ever seeing ot having heard of a DWM or Military Mauser J-Block.
Regarding Military Mausers, the K-Date began with a low no suffix and then went through the G-Date, 1936 and most of the 1937 before it hit the first Z-Block. Then they built the 1938, 1939 S/42 and most of the 1939 Code 42 before they hit the second Z-Block. Then came the 1940, 41 Code 42 and then near the end of the byf 41 production they hit the third Z-Block. Finally they quit production with the end of the L-Block (actually extremely early M-Block).
Then, they used remaining parts (maybe made a few new parts) to complete the M and Lugers in the N-Block for the Portuguese and Bulgarian Contracts.
I don't know the details of the Imperial Luger Numbering Schemes with all the "Special Contracts" intertwined with the Military Contracts. I suspect from the data I have seen, the Military Contracts were alpha-numeric, while the "Other" Contracts were strictly numeric. Perhaps we can get some help from the "Grip Safety Guys"