Inheritance springs to mind, although it's semantically backwards. I like instantiation time. Or, to take a non-tech word, how about spoor? You can lose track

Inheritance springs to mind, although it's semantically backwards. I like instantiation time. Or, to take a non-tech word, how about spoor? You can lose tracks after time, they can be more or less clearly defined and they have a lot of metaphorical associations.