It is easier to make the transition from formula or breast milk to whole milk by slowly adding the milk to the formula/breast milk. For example, offer your baby a sippy cup or a bottle with 3/4 formula/breast milk and 1/4 milk.Offer this mix for about 1 week and then offer 1/2 formula/breast milk and 1/2 milk for another week. At or around “week 3″ you should be at a 3/4 milk and 1/4 formula/breast milk mix. have also found it easier to make the transition by using a “special” cup. Purchase a new and colorful cup and make a big fuss over it; but do not make a fuss about the milk, just fuss over the cup. If your little one is still on a bottle, buy him a special bottle.