I just stated my support for your idea but that doesn’t mean it’s possible. Idk if that’s even technically possible.
For now, you can create a date Custom field for customer called “deal won date” or whatever.
For existing customers, you can get this information from clicking on the tiny History button at the bottom of their view screen and use that to fill your field.
Cheers had a little chuckle there, all good … Yeah the tiny history button suggestion is really impractical even if it worked. In fact it just comes up blank for a number of customers I tried it with. Anyway hope search gets sorted so that simple information can be produced or reveal at least.
Digressing here - Without adding custom fields to Customer info (which is too hard to add to history) can Custom Reports look at customer inception / onboarding / creation date data?