8.5 lbs is the carbing pressure at 34 degrees, assuming you're using the "set and forget" method and want about 2.4 volumes of carbonation. It will take 10 days or so to fully carb at that pressure and temperature, and it needs to stay at that pressure and temperature if you want to maintain that level of carbonation, so ideally it will be your serving pressure as well. That's the way the carbonation charts (and beersmith) works.
If you want to try and get it carbonated faster, you can try giving it more pressure for a couple of days and then dropping it down and maintaining the 8.5 lbs. It's called burst carbing, but it's somewhat inexact and everyone seems to have their own technique for it. Be careful, you can overcarbonate your beer if it's hooked up for too long at higher pressure.
Personally, I prime the keg and naturally carbonate (and age) at room temperature for 2-3 weeks, then chill and hook it up to the CO2 at the indicated pressure. But if you want to force carbonate it's best to do it chilled. At room temperature (70 degrees) you will need to keep it at 27 PSI to get the same carbonation level as you'll get with 8.5 PSI @ 34 degrees.