For baby's first feeding, start with 1 tablespoon. Increase amount as bb's appetite increases. You may mix the cereal with milk or water. You may feed your bb cereal in between 2 meals, usually in afternoon teatime.
Milk is good for bb. Why would you want to replace the milk? My bb is now 17 months. Even though she started solid food long time ago, she keeps drinking milk 3 times a day. Her daily schedule is as follows:
Morning: Milk
Noon: A bowl of rice with meat & vegetables
Afternoon tea (around 3:00 p.m.): Cereal or biscuits
Around 4:30: Milk before her nap
Dinner: A bowl of rice with meat & vegetables
Before bed: Milk