First of all: Definitely set feeding times and control the amount fed.
Second, I'm not criticizing, just suggesting:
Since you posted here I think I'm obligated to ask if you've thought about feeding a higher quality food. Have you? It will be cheaper for you and your dog will definitely be happier! Science Diet is mostly grain.
Science Diet:
Lamb Meal, Brewers Rice, Rice Flour, Ground Whole Grain Wheat, Ground Whole Grain Sorghum, Corn Gluten Meal, Cracked Pearled Barley, Animal Fat (preserved with mixed tocopherols and citric acid), Dried Beet Pulp, Soybean Oil, Chicken Liver Flavor, Flaxseed, Potassium Chloride, Iodized Salt, vitamins (L-Ascorbyl-2-Polyphosphate (source of vitamin C), Vitamin E Supplement, Niacin, Thiamine Mononitrate, Vitamin A Supplement, Calcium Pantothenate, Biotin, Vitamin B12 Supplement, Pyridoxine Hydrochloride, Riboflavin, Folic Acid, Vitamin D3 Supplement), Choline Chloride, Vitamin E Supplement, Taurine, minerals (Ferrous Sulfate, Zinc Oxide, Copper Sulfate, Manganous Oxide, Calcium Iodate, Sodium Selenite), preserved with Mixed Tocopherols and Citric Acid, Beta-Carotene, Rosemary Extract.
Food Fragments: Lower cost by-products of another food manufacturing process. Examples include wheat bran and brewer's rice (a waste product of the alcohol industry).
Corn: Corn products are difficult for dogs to digest.
Rice Flour: All of the naturally occurring vitamins have been leeched out by the processing.
Animal Fat: Animal fat is a "generic" fat source that is most often made up of rendered animal fat, restaurant grease, or other oils too rancid or deemed inedible for humans. Look for a named fat source, such as poultry or chicken fat, that is naturally preserved.
Salt: While salt is a necessary mineral, it is also generally present in sufficient quantities in the ingredients pet foods include. Just like for humans, too much sodium intake is unhealthy for animals. In poor quality foods it is often used in large amounts to add flavor and make the food more interesting.
Canidae:
Chicken Meal, Turkey Meal, Brown Rice, White Rice, Lamb Meal, Chicken Fat (preserved with Mixed Tocopherols), Herring Meal, Flax Seed, Sun Cured Alfalfa Meal, Sunflower Oil, Chicken, Lecithin, Monocalcium Phosphate, Potassium Chloride, Choline Chloride, Linoleic Acid, Rosemary Extract, Sage Extract, Dried Enterococcus Faecium, Dried Lactobacillus Acidophilus Fermentation Product, Dried Aspergillus Oryzae Fermentation Extract, Dried Bacillus Subtilis Fermentation Extract, Inulin (from Chicory root), Saccharomyces Cerevisiae Fermentation Solubles, Yucca Schidigera Extract, Mixed Tocopherols (source of Vitamin E), Zinc Amino Acid Chelate, Manganese Amino Acid Chelate, Iron Amino Acid Chelate, Copper Amino Acid Chelate, Cobalt Amino Acid Chelate, Vitamin A Supplement, Vitamin D3 Supplement, Ascorbic Acid (source of Vitamin C), Niacin, Thiamine Mononitrate (Vitamin B1), Riboflavin (source of B2), Beta Carotene, Calcium Pantothenate, Pyridoxine Hydrochloride (Vitamin B6), Calcium Iodate, Folic Acid, D-Biotin, Sodium Selenite, Papaya, Vitamin B12 Supplement.
Pet Food Direct prices:
20lb bag of Science Diet: $23
20lb bag of Canidae: $21