In those cases I may suggest any date/year significant for you. Or maybe for some close friends or family members, and then maybe gift the knife to them.I have a 001 of my own knife, but a couple of times during my life, I've been offered a pic of serial numbers, and couldn't think of anything!
From all my "knife experience", only thing better then having great knives is to gift great knives to great people. I specifically enjoy to gift a person who is not into knives at all with something unique, i mean not necessarily expensive and fancy, though decent, and something they most likely would have never encountered in their life otherwise, even if they happen to visit some local knife store. That joy of giving is truly something special.