Every July I move to Los Alamos, NM ~7,200 ft. from Santa Barbara, CA ~20 ft. (I've been doing this for 4 years now), then back down elevation in September.
I usually take 3-4 days slow, just walking around 3-4 miles a day. Then 2-3 days jogging 3 miles, after that I feel fine. Your body may take a little longer depending upon activity and nutrition, but just eat a ton (try to keep it somewhat clean) and you'll be fine in 7-10 days. Your red blood cell count will take a couple weeks to get up there, but eating high iron foods will get more hemoglobin % and will counteract the slowness of building RBCs
Some of these guys may be right, but like I said, I've been doing the same routine for a few years and it seems to work out for me. and yeah, dropping in elevation is always fun, you definitely feel great for the first few days before your body starts dumping RBCs