I don't know about corn snakes, but my ball python ate for me last night as soon as I dropped the rat in, and I fed him a pinkie 4 days ago. I left the rat in his feed cage with him, but the rat was in a closed paper bag.

Vincent picked up the scent, and when he started to go for the bag, I took it out and put the rat in, and 5 seconds later... dead rat.