Considering a retired breeding cat

If you are looking into welcoming an adult cat, a retiree is a great option! As an alternative to a kitten, they are a wonderful way to get introduced to a breed that you are considering. The main appeal to taking in an adult cat is the predictable personality. Oftentimes, breeders will share extensive details about an adult they are looking to place in hopes of finding the perfect home for them. They will be able to share if the cat has done well with kids, dogs, other cats, traveling, grooming, vet visits and handling.
Additionally, these cats are often fully health tested and may even be titled in the show circuit. Meaning that you will 100% know that they are free and clear of health issues as much as possible, and sound in body and mind. Some breeders bring their retired cats that are looking for homes to the show halls, so that they can meet prospective families and get a better sense of if the dynamic clicks between the cat and the new family. If there are any health concerns or behavioral traits that require your attention, you will be informed right away and with the breeder's help, you will be able to decide for yourself if it's an appropriate fit or not for you.
The cost of a retiree is often less than that of a kitten, so this option can be more reasonable for some. Depending on the circumstances, the cat may or may not come with a health guarantee, but you often have lifetime breeder support regardless.
Now, let's say you're on the path to welcoming an adult, congrats!
Here's what you can do to prepare:
Talk to your breeder about the individual cat, get a good understanding of what things to expect. Ask what things would make the cat most comfortable, such as toys, treats, types of foods, affections, etc.. Prepare your home in advance and get things ready for their arrival. Set up a small area for your new kitty, such as a bathroom or bedroom. Make sure they have food, water, litterbox, a bed and somewhere to tuck away if they are nervous. 
A great tip to help them get to know you is to take an old T-shirt/blanket and wear/sleep with it the night before your kitty comes home. Then give them this item in their new space to help them familiarize with your scent on an item of comfort. 
Once they have arrived, it can be an exciting time for your family. Please be patient though, and give them time and space at first. Their entire world is completely changed, they may feel overwhelmed. The most important thing the first three days is to make sure they eat, drink and use their litterbox. A bathroom set up is great, because you can visit them for short intervals throughout the day in a neutral way. 
After the initial couple of days, you can expect to see some strides in confidence. They'll start to be curious, may start to be more comfortable in your presence. Take this time to start your initial interactions, use those pointers from the breeder to help build confidence with your kitty. Treats, toys, etc.. If your cat seems open to affections, pet them slowly and talk to them softly. Still keep the interactions short at this point, but you can make them more frequent. Maintain a positive interaction as much as possible. If they want to go into hiding, allow them the space and try again later-this takes a little building up to sometimes!
After about three weeks, your cat will be more familiar with the environment and with you. You can allow more exploring, make sure they continue to eat, drink and use their litterbox. During this stage, this is a great time to start the introductions to children, dogs or other cats. Start with smelling through a door, or bringing an item to your new cat to smell. With children, some parallel play is a great way to start. If your cat likes interactive toys, this is an amazing way to introduce your cat to children. Again, keep the interactions positive and short. Let it happen naturally and allow them to come out of their shell in due time. Children often love to be involved, have them help you feed and water your cat, clean litterbox and pet them calmly too in this stage. A great tool when introducing other pets is to utilize a cat tree/tower. Give your new cat a high spot to observe from at a distance.
At about three months, your new cat should be content in your home. They should be comfortable in your space, with you and other family members as well as pets. At this point, this is when you can really start to form a strong bond built on trust. They should be able to navigate your home and they may have established their favorite spots by now. Feeding times and play times should be a favorite part of their day. You will really see their personality and true self by this point if everything went successfully.
If throughout this process, you are unsure of your progress-reach out to your breeder for tips and share your experience. Some cats have a harder time than others, remember everyone is an individual and use these steps in the timeline to have the best success. Some cats may not be nervous at all, and that's okay too-still honor the system and take it slow so it remains a very positive experience for everyone.
Welcoming an adult cat, especially a retired breeding cat, is a special thing. If you are lucky enough to bring one home, it is a worthwhile experience.