Please, include a photo of the front of the watch. That will make it a tad easier for us to help You out on dating Your watch
First digit: Year of manufacture (You will have to know a little something about the movements or the models to get this one absolutely spot on)
Second digit: Month of manufacture (1-9 is jan-sept, o is october, n is november and no price for guessing what d is for)
Four last digits are the production number of the unit in that month
The 7S26 has been manufactured since 1996 so if You want to date f.i. a SKX007 with the first digit "7", You will have to take of the caseback to see if the watch is a 7S26A or 7S26B movement. The "B" movement was launched in 2006 - as far as I know.
Dating vintage pieces requires some knowledge on the models. Here the 8 digit number on the caseback can sometimes be helpfull. If You are stuck with a watch, just post a pic here - everybody is willing to help out if they can