transitioning new puppy off of a crappy food....

 You didn't hurt him - just watch for dairy intolerance later.  Some people go bonkers and dump a cup of yogurt on top of the kibble if a little puppy has the runs.  They just aren't set up to tolerate that much dairy.

 I would go "cold turkey" in small amounts supplemented by probiotics, yogurt and pumpkin.  I've never had any trouble w/any of my dogs going from food to food and I have 5 of them. What is most important is that you support the digestive system... the probiotics will boost the amount of good bacteria in the gut, as will the yogurt ( it will also soothe/coat the stomach ) and the pumpkin will help with any loose stools.  See if you can order some Prozyme and Arc Naturals Easy Digest or just get some acidophilus capsules and sprinkle them into the food with some bromelain or papaya enzymes.