Date format variable

How do i get this: When you choose to print, and the popup box comes up and you choose the configuration for exporting PDF, you click print and then the file ready to be saved. The automatic generated name that is suggested to be the file name, in there i would like a variable to be the last 2 digits of year, the 2 digits month, and 2 digits day. Many people reference guides to do this, but all the links take you to a page that does not work anymore.

Can anybody help with it?