Both of our cats were rescues - one settled very quickly, but her underlying nature was so laid back she was horizontal anyway.
The other one by nature is much more highly strung (to put it mildly). We rehomed her at a year old just over 12 years ago, and it took her months to be vaguely chilled out and approach us on her terms, years to be able to get close to her when she was asleep without losing all the skin on your arm, and even now I won't let DS approach her when she sleeps as she can still easily startle awake with claws and teeth flying (although most of the time now claws are gloved if she has a pop for any reason). For the first few months we had her home, she used to sleep in the top of my wardrobe along the shoulders of my clothes - made trying to get something out for work very interesting in the mornings, as more often than not would have to withdraw bleeding fingers from wardrobe after getting another bop...
Funnily enough, even now, although you can pick her up for a cuddle, and she relaxes completely and drapes across your shoulder, she HAS to be up on your shoulder, and you have to be standing up. She still won't tolerate being held in your arms, or you sitting down with her, and will growl and spit until you either stand up or let go...
Its been a very long road with her, and on the whole she's very chilled out now, but I've got a feeling that's as much to do with age as anything else, she's 13 now and starting to slow down. Will miss her like anything when she finally goes, as to see the change in her over the years has been so incredible.
I guess what I'm trying to say is give yours time. We spent months convinced Socks hated us, and that we'd done the wrong thing, but little improvements were creeping in, and that gave us hope. Let the cat do things on her own terms - coming to you, rather than having hands stuck out at her; 6 days as said by others is nothing, and she's quite a bit older than Socks was when we brought her home. I'm sure she'll settle eventually, although she may still have some "quirks" that you'll have to accept, ours is proof of that!
Good luck 