Too many variables to determine that for everyone, it could be anywhere from 10 minutes to 2 hours. Just be patient is the best advice I can give.
I tried for about 30 minutes originally, installing, canceling, restarting... it just wasn't doing anything for me, install was very slow. BF tried installing for me, and after 40 minutes it wasn't at 50%. DVDRom is fine, computer is fine. So he created an image file on his laptop from the dvd, transferred it to my pc, and installed it from the HD rather than the dvd, it's running now, very quick. So something is probably screwed with my disc.
Thank goodness I have someone here who knows this stuff cause i would have been lost >< I know EB wouldn't have exchanged an open product so I would have had to go through SE to get a sealed package to get exchanged and would have taken weeks... had that happen with my SIMS.
So be impatient like me ;P If it seems like it's going too slow it probably is.