Always keep a quart of reconstituted non-fat dry milk product mixed up with water in the refrigerator, ready to use in cooking. Label clearly. Then you can save on having to use regular drinking milk for cooking purposes. Much more economical.
I`ve been using dry milk powder in cooking/baking for years. My method is even simpler I think...I put the milk powder in with my other dry ingredients and the water in with the liquids. Has always worked well for me.