Gentlemen:
A word of caution! One of the motorcycle clubs I am involved with has a really nice documentation about yearly VIN numbers and production dates in a certain month. Even there it is extremely difficult to determine the exact day/date when the vehicle rolled off the line. You just can NOT use simple math to narrow the date down. Many factors contribute to that. In any given year, in any specific country, there are certain "holidays" or plant closure days due local schedules, school vacations, weather issues or even worker's strikes. It is next to impossible to determine a date when any vehicle rolled off the production line. Another unknown is, if the specific vehicle passed final inspection and may have to be routed back for rework, which would delay the "roll off" date.
The plant in Untertürkheim is in the state of Baden-Württemberg and was subject to several "church" holidays, that were only observed south of the "Weisswurst-Equator" which will throw any math base don days worked per month off.
Besides, I relay don't know what the point would be to know the day or even the month of manufacture. If you can place your car into early, middle or late of a model year, that should be great.
Easy for me to say, because I have a date of delivery in my card of December 16, 1970 and together with the VIN number I can comfortably say it was a December 1970 production