carfield: Try to start with Baby Toothpaste without any Fluoride in it so that you don't have to worry about the baby ingesting too much fluoride which will turn the teeth yellow. You can try the brand First Teeth (contains enzymes to clean the teeth & gums), available at Jusco's baby dept. (& maybe WingOn & Chico).
You can switch to adult's toothpaste only when your baby is older and has mastered how to rinse without swallowing the tap water and toothpaste.