What would be the typical time frame of a correct dated engine block prior to the car's production date. How much time before the production date of the car? In example, a car with a production date of 10A, what should the range of dates be on the engine block?

I've found that 4 weeks prior is frequently found on the original cars that I have. I would suspect the two weeks either side of that would also be correct. Special engines may sit around longer.

Thanks for your help!