I wasn't sure exactly how to tell if it was inflated properly, so I just stuck my finger up there and felt around for smooth edges (yep!), rotated it a bit, tested the suction, and put on a pad to test for leakage. I've had it in for about 3 hours now, and have had absolutely no pain or other problems.
Oh man...if it's ALWAYS this nice, I KNOW I will never touch another tampon or pad in my life. That is EXCELLENT news!