Its one of the Nato canteen cups, like 3/4 way full. Water was cold...was sitting in my jeep from the day before. And, yeah, stove times vary greatly from what is claimed, to what they actually produce. I have a nice little high speed canister stove I use for backpacking trips that claim a 3 minute boil. I usually get it between 3.5 & 4. Which is fine for me.
Your outdoor mentor sounded like a smart man. Mine I learned mostly on my own, with the exception of some classes in the army.
The boiling time doesnt really matter to me, as, well, again, this is essentially a fire I was cooking over. I still like being able to cook on a fire, with no mess afterwards. You've done your mentor well, and thank you for sharing this neat little stove with us!