Is it love?

[Slim]

I will venture to say that for the OP, the quarantine train left the station a while back...

Does it have to be at my own place, or can it have been done with the original owner?

That would be an original owner that you trust very much. Personally, I prefer to do it myself so I can observe and work with the animal.

I personally don't think it matters where its quarantined as long as you can see that it hasn't been sick for some time.

Which, as you alluded to, is hard to do when the snake is not in your possession.