I highly, highly recommend waiting to hit Terrifier until a bit after 6:30 (but before 6:50). It may seem counter-intuitive, but if this weekend was anything to go by, everyone with early entry on the upper lot by that time will have waited for Terrifier and moved on to Poltergeist (or raced to the lower lot to try for Jason or Five Nights).
When we arrived on our RIP tour around 6:40 or so, the Terrifier queue was empty, but Poltergeist had an easy 20-25 minute line. By the time we finished our runs of Terrifier and Poltergeist, the general admission folks had arrived, putting Terrifier at a 50-minute wait and climbing. It's a narrow window, but it can save you a lot of time.
I'd save Five Nights for last using this strategy if you're okay skipping the chainsaw chase-out.