I got Kacee at 6 weeks. She weighed 2-1/2 lb. I started out by grinding her puppy food, adding water, and adding about 3/4 teaspoon Gerber chicken with chicken gravy baby food. She loved it and has never been sick. (Just be sure you don't give them any baby food with onion ingredients.) She still has trouble eating the dry puppy food, so we just sit and I feed it to her one pebble at a time for a snack.
I now feed her two meals of that and two meals of canned puppy food. I've probably created a bigger baby, but so be it if I have! Muffin was spoiled rotten, too. However, if anyone has any better ideas, I'm open to hearing them, too.