Animal shelters are an excellent place to adopt cats. Some pet food stores have adoption centers and you can contact the people who run this.
There is a Pet Smart store in my area and they have an area where there are cages for cats who are up for adoption. There is an info pack in front of the cages so people who want to adopt a cat can see the date of birth, shots etc. You could also advertise on store bulletin boards or by word of mouth.
Ask friends if they know of any one who’s cat just had kittens as they usually want to give one or more away.
My two cats, Panther and Cheetah, came from a lady who was rescuing cats in her home. She was a friend of my cousin and that’s how I found out about it. They will be 8 years old in May.