It matters but a lot less than you may think. Every chicken breed has been developed by inbreeding. Every grand champion chicken at a show was developed by inbreeding. Basically, when you are developing a breed or a champion chicken you are eliminating genetic diversity in the traits you want. But you want to maintain as much genetic diversity as you can in the traits you are not breeding for. Breeders have techniques for that. It can get complicated if you get into the details.
But let's address your specific situation. For thousands of yeas a standard model on small farms has been to save replacement chickens from your flock. Breeding siblings, parent-offspring, or close cousins. Depending in the size of your flock, the number of roosters and the number of hens you keep, you can go several generations before genetic diversity becomes a problem. With one rooster and nine hens I'd think four generations is realistic. Then you bring in a new rooster and start over. Keep your hens. Hatcheries we buy from usually use a version of that system but they may have 20 roosters and 200 hens in a pen. They can go several decades without problems. We can't because we don't keep that many.
There are some tips or tricks. Do not breed defective chickens. Never breed one you feel sorry for. Be ruthless in deciding which are your best breeders. You are not going to develop a new breed or a show chicken with this method but it's been used for thousands of years to keep small farmers in meat and eggs.
