I think both oldest and youngest person to achieve a 1st KS would be an interesting "record" to track. With the former, 1st KS seems more relevant than simply oldest person to KS since the development of the skill to do so could have occurred many years prior if you'd KS'd before. I had wondered about this before the OP posted, but guess I'm nowhere close unless I wait 15 or so years before getting there myself...which I'm hoping not to do.
So I guess the record for oldest person to 1st KS for now stands at:
Age = 56 years, 4 months, 3 weeks, 5 days
Anyone know the youngest person to KS?