When we found our little Tigger, she was about 5 weeks old and I am amazed how friendly she is now at 6 month! We found her near a quilt shop in PA and I think people had been feeding her. When we first brought her home she was a little shy so we put her in a closed off room since we had two other cats at home. We added a soft cat bed, scratching post, food dish and water dish and several cat toys (balls, little fur mice) and a blanket that my other cats had been sleeping on. We would go in her room several times a day to sit on the bed, talk to her and let her come to us. We brought her home on a Saturday and I had her vet checked (she had mites and worms) on Monday. The vet said she was about 5 weeks old; she was eating soft baby cat food so we never had to bottle feed her. We knew we were keeping her at that point
It took about a week but she got used to me, my husband and daughter. I think it helped that she was so young though. She apparently had not been weaned by her mom so she started suckling and kneading her cat bed. Never had a cat do that and we have had many in the last 28 years!