You shouldn't let a kitten or a cat outside at all. It is a markedly bad idea. Open your curtains and let kitty look out the pane. Putting a 6 month old kitten outside will surely terrify him/her...it would be approaching putting a 6 month old human baby outside to crawl around. I know that individuals think cats should be outside, but that isn't true. They can catch diseases from birds and rodents that they may encounter and/or may be run over by a motor. They can be hurt by a cruel human or killed by a coyote or other predator. We have lost 7 cats on my street alone to coyotes because people expect they should allow their cats to roam; that they are being mean by making them stay indoors. Get lots of toys and let them look out the window. Inside is a much safer place to be.
I don't urge letting cats outside to roam unsupervised. I know some do, so I usually tell them to any train to a harness/leash or build/buy a cant enclosure where the cat can be outside but protected.
There are too copious dangers out there (cars, other animals, cruel people that exterminate and torture cats) to be worth just letting your cat run unsupervised.
I would wait til the stitches have been taken out and that you consistency she trust you then you can let her out.
My kittens went out at 4 months and are without fault fine and healthy. My oldest cat is 22 and has been tolerate out all his life and he's totally healthy. Our cats would budge crazy if they were kept in.