Decorative Life Preservers When Considering The Established Date For A Home, What Date Do You Use? Date Of Purchase Or Occupancy?

When considering the established date for a home, what date do you use? Date of purchase or occupancy? - decorative life preservers

I bought a jacket design for the lake house with my parents for Christmas, and I'm not sure if the date of use. They have completely remodeled the house, so that the date or the purchase and work differently.