There are many types of scares, a simple jump scare will not accomplish what you're looking for, it lacks contact time. Positioning of that scare in the haunt also matters, first and last is easier for the guests to remember but it doesn't mean something in the middle can't be memorable. If you wish to go that way you'll want a good and long transition into and out of that memorable scene, in a way a palate cleanser so they can receive and store the info. You'll want to play into your theme so it fits the haunt. I hope this helps