To give Lax-A-Day to a 7-month-old baby, you should first make sure they are getting enough fluids and consuming fiber-rich foods like sweet potatoes, fruits, vegetables, and oatmeal. This will help soften their stools. You can also try increasing the frequency of feedings to every 2 to 3 hours and giving smaller amounts at a time. If needed, you can give a tasteless and odorless powder like PEG-3350 (LAX-A-DAY) mixed in a small amount of any liquid to help with constipation. The amount of powder to give is based on your baby's weight, with the general guideline being 1 gram per kilogram of weight. Your pharmacist can show you how to measure the exact dose, as only adult dosages are typically listed on the packaging. If you have any more questions, feel free to ask!