Weaning should start at 4 weeks old. Introduce kitten formula and dry kitten food softened with warm water to form a mash. Complete weaning will take about 2 to 4 weeks. Prepare for things to get a little messy. Be sure to prepare fresh formula and food each day. Momma cat will show her kittens what to do. Now is a good time to introduce an easy access kitty box for potty training. Video to follow.