When did Google first find my domain?

Is there a method by which to find out...

[sandpetra]

Is there a method by which to find out when Google first encountered a specifi URL (no matter how many years old?)

[antoine france]

I don't think there is a method.

I asked many time myself to know if a site is sandboxable?

A goog way to check is maybe to verify if a domain was backed up. For exemple in Waybackmachine :
[archive.org...]

But there are not so much site inside.