Clarification on Drones respawn

Hey, I've asked EVERYONE about drones respawn and I almost always get different answers. The ones that actually know just say they have a "Feel" for it. So yeah, does the respawn timer start after the LAST drone is killed? And is this 3 mins? This is what it's looking like to me...

Or is it something else? The same for the huge 200 points one, how are we supposed to know when this one will spawn?

From what I've gathered and not bothered to thoroughly check myself, drones spawn 3 minutes after the last one dies in the current set. Node spawns around the 22:00 mark on the Duty Finder's countdown.

I concur with Kaisha, though I, too, have not really thoroughly tested it. Still, it certainly seems this way to me.