For many attractions, part of your wait is inside in a pre-show area. As I recall, for this attraction, you are outside in line in the sun the whole time. The door opens, about 24 people are let directly into the room where the show happens, and everybody else continues to wait in line outside.
When the show is over, you exit into the gift shop. Be warned that it may be really, really crowded in there. It may be difficult just to walk through the crowd to get to the door to get out. I don't know how your child would feel about that.
People staying at Universal hotels can get into the park early, and are likely to do Forbidden Journey and Dragon Challenge first, then do this. I would be concerned that you may have a long wait for this attraction even if you are at the park at rope drop.
Also - I'm surprised the crowd levels are expected to be low on October 12, since that's Columbus Day weekend.
I'm an admitted pessimist, so you might get more positive input from other people.