lol! I just came to make a post with the same topic line. Although my circumstances are a bit different.
I just got my snake Friday, and fed him for the first time today. I went ahead and fed him live and in the enclosure for the first time, to be sure that I got a feeding response. Like you said, I turned off all the lights and closed the blinds, but I did that anyway just to play it safe, I hadn't tried any other way.
It was pretty exciting, he took down two adult mice. The first one, I grabbed by the tail and dangled it in front of the entrance to the hide he was in. I did it for a while, and didn't get a response. So, I dropped the mouse in and waited.
I waited and watched for a couple of minutes and I finally saw his little head poking out of the hole. Finally, the mouse wandered back over to that side of the tank, and....WHACK. Got 'em.
I left him alone for a little bit to get it down, and left the other mouse in the box on top of the screen lid. By the time I came back, he was already hunting for the other mouse. He made pretty short work of that one.
Overall, it was very exciting, because I was definately worried about the first time. Especially because the snake is underweight in the first place.