Determine date activated?

Not that I know of. If you still have the packaging, you might be able to see when it was manufactured.
 
Dial ##634# > calls up the Lifetime Counter

I believe this shows the amount of time your screen has been on.

I'm on a new Lumia 640 and it shows 27:13. No way I talked that long, I've had it powered on in use or standby for 6 days... Seems amount of screen use is the most likely stat showing in that range...

Not a direct answer, but it's all I got.
 
Dial ##634# > calls up the Lifetime Counter

I believe this shows the amount of time your screen has been on.

I'm on a new Lumia 640 and it shows 27:13. No way I talked that long, I've had it powered on in use or standby for 6 days... Seems amount of screen use is the most likely stat showing in that range...

Not a direct answer, but it's all I got.

You know what? I forgot that my wife used my phone to talk with her mother. That's where I couldn't reconcile the time.

It is 27minutes:13seconds Talk Time. D'oh!