Originally posted by: SNESNESCUBE64
I do it based on the latest date on any chips on the pcb. They should all have a date code in the format of "yyww". For example, a date code of 8849 implies that the chip was manufactured on the 49th week of 1988. This method is not exact, as it will have been made AFTER the latest date, but this method is a good gauge in my opinion. Serial numbers, although in order, do not provide any form of date. Also, welcome to the forum!
Maybe NES serial numbers don’t contain date information. But serial numbers as a generalization may or may not depending on the numbering scheme