Yes, it opens at the same time as the regular entrance. It is extremely close to Grizzly River Run and Soarin' as netenyahoo mentioned. On a couple of occasions, we grabbed FastPasses for one of the two on the way back to the GC, took a break for awhile, then went back in at the stated time.
actually, you could get a Fastpass for both at the same time. Grizzly isn't on the same Fastpass system as Soarin', so you can get a FP for both at the same time