Let me add. As I said already. I live at 8500 ft. I'm hunting the muzzleloader season, and i've started to go to treeline everyday. It took me 1 1/2 weeks to start to feel normal again. It felt like I had lead boots the first week, and I was coming from 8500ft. If I didn't prepare early. That 1 1/2 weeks would have been the whole hunt, and I wasn't hauling out elk meat.
I'm an old fart, so it might not be as bad for you if you're young. I would still try and come here early so you can go to high altitude in steps. If you come here and go right up to over 10,000ft. You won't be happy.