4-8 weeks

It is important that all your personal pets are fully vaccinated, free of intestinal parasites, and have flea prevention. Have the kittens stool checked with a fecal test, especially if they are having diarrhea. As long as everyone is clear the kitten can explore safe spaces in the house. It's at this time that they get acquainted with other animals, household sounds and build fine motor skills. It is important for adoption that kittens are socialized with people, animals, and general household noises. It will build their confidence and their social interactions. If your personal pets do not react well to the foster kitten, do not push the issue. It's their furever home and the kitten's temporary home. A two week quarantine is needed for any new kitten brought into your home no matter their age. This includes keeping new kitten away from your personal pets, as well as foster kittens that may already be in your home for at least two weeks. 

When a kitten has a bowel movement away from their sleeping area they are ready for a litter box. I use box lids with litter to start with. After kittens are pottying on their own, there is no reason to potty them. They are starting to hear and see better, and incisors are starting to emerge. At this time a slurry of wet kitten food and warm water can be offered. Kittens wean at different times. Some sooner than others, and some still want a bottle while eating wet food. The kittens are less wobbly on their feet, are more confident, and are ready to explore, and learn to play. 

The kitten should be weaning onto wet food soon. Make sure to weigh the kitten every day to ensure there is no weight loss during this transition period. Kittens may also want a bottle in the morning and/or night. I believe in letting the kitten decide when to stop the bottle. Be sure to run the dishwasher, washing machine, flush toilets', close doors, run the vacuum, sweep, etc to get the kitten used to these types of noises and activities. They also need to be stimulated with play time. Give the kitten a shallow, sturdy litter box. I prefer oil pans from the dollar tree. You can also find shallow bowls there. 

Most kittens have given up the bottle and are eating wet kitten food confidently. Give a shallow bowl of water at this time. Play is a big part of their day. They need to be kept in a safe, kitten friendly area. Keep toilet lids down. 

The kitten will become more playful and their eyes will transition to the adult eye color. Give small hard kitten food mixed with wet kitten food. Make sure kitten has access to clean water. 

When your kitten reaches 2 pounds, this is the time to start vaccines. If they have not already had a fecal test, dewormer, and flea prevention, they need it at this time. They need 3 rounds of vaccines, 3 weeks apart.  These vaccines are FVRCP, Feline Viral Rhinotracheitis, Feline Calicivirus, and Feline Panleukopenia. Talk with your veterinary clinic to  setup a vaccine schedule.