Found more info in Fred Datig's The Luger Pistol. On page 166 he breaks down P.08 monthly acceptance during WWII. Also I read somewhere that two other letters besides "j" were not used for military numbering. So 9999z probably equals less than 260,000, maybe 240,000.
Subtracting the 41 byf SN# 7345u (207,345) from 240,000 leaves about 32,655 pistols made until the rough date of November when the "odometer" flipped over again. Assuming that date was Nov 15th maybe 6,500 pistols were accepted in Nov. plus 12,230 in Oct. and 13,250 in Sept which makes up 32,000 pretty quick. Of course some of those may have been made by Krieghoff but even so August looks good for that SN, maybe September.
Ok I'll shut up and go back to my corner. You guys can quit laughing! Newbies can get over exuberant...
But am I close?