I think at 3lbs and 13 weeks, he'd be fine during the day. If you are worried, you could always fill a Kong with some kibble and seal it with frozen yogurt, etc, so it keeps him busy and he's eating a bit throughout the day.
Jackson was a big boy -- he was already 6lbs by the time he was 12 weeks old. lol. He's now a healthy 16lb adult. I wouldn't worry too much about him being "fat" or anything - rarely are pups actually overweight. If he acts hungry, feed him. But a lot of dogs will act starving even after they've just eaten. So I think it just depends on the dog. I wouldn't go over 3/4 cup per day personally. It looks like the bag recommends 1/4 - 1/2 cup per day for puppies 1-3 months old and 1/4 - 3/4 cup for 3-5 months old that are going to be 6-10lbs as an adult.
Oh, TOTW = Taste of the Wild.
