Fruitbat,
Just about all the aircraft produced in contracted block to be on the production line in November and December 1944 were being OPERATED in January 1945.
In otherwords, most of the FW-190A9 production is in use in 1945.
That is typical for all production aircraft.
White 1 for example, rolled off the production line at NDW, went through a week of acceptance flights to ensure contract compliance before being transferred to the Luftwaffe, then went to a distribution node where it sat for 3 weeks before being issued to JG5.
The last aircraft in White 1's production block rolled off the assembly line on the 20th June. The contract block was from May to June 44. After being assembled, White 1 spent until the 13th of July in test and acceptance flights before becoming part of the Luftwaffe inventory.
It was then shipped to the depot in Anklam where it was finally issued to JG5 in mid-August 1944.
Any production block that you see means a lag of ~30-60 days to Operational use.
I know you don't deal with reality very much in airplanes so reading the production block dates mistaking them for operational dates is expected. It is very rare that anything is "poofed" into existence operationally. There is always some lag time.