+1 agree that you will notice but it won't stop you from having great rides.

-1 disagree that you acclimate in any way in a day or two. I don't have a link but research has shown that after a few days the cumulative effects actually wear you down as you acclimate, which takes a couple of weeks or more. So either get there a few weeks early or hit the hills as soon as you get there before the altitude starts to wear you down.

Btw I live and ride at 200' and I've been in Colorado for about a week riding at between 9,000 and 11,000 feet or so (Breck / Vail area). If SD is anything like it is here you're gonna have a great time.