I'm curious about the 'getting to know' time line as well.
I do think you're onto something though with the fantasies I mean we all do it, even in minor ways. When I know I have a check coming and a cheat day I start thinking about what I'm going to order, then once I get it I can't wait to rip into whatever I've ordered. Think about when you think about vacations and how you 'just can't wait' to do everything you want to do and how sometimes you get so overwhelmed you don't know what to do first. It wouldn't surprise me if killers find themselves in similar situations, especially since I would think, they can't vent like the rest of us to just anyone, or anyone at all. So it would build and build and build until yeah, maybe as soon as they get the fly in the web so to speak they have almost no control and just pounce so to speak. They spend so much time controlling their urges that once they're so close there is no control anymore
Maybe there is no uniform style? Israel Keyes said, you go with whatever comes your way or so, meaning, one can have the preferred style, but whenever the urge comes and the opportunity is there, he merely acts on it. So he ended up with many kill kits buried around the country, in case the urge would come, and they still don’t know how many victims he had.
Since you mentioned a check and orders, I remember my own shopping style. I have nothing else to compare to as I am very placid, but shopping is something else. So shopping - I don’t have the time to try the clothes on, better to overshop, then try at home and return half back. It is between an urge to buy and a lot of things around, and if I start choosing, I shall come home empty-handed.
But perhaps there are different shoppers? They shop only when they need something. Never overshop. Probably spend a lot of time researching. Finally when they buy they get exactly what they need.
Perhaps some killers are like this? Maybe they don’t leave kill kits all over like Keyes did, in case the urge is there. Perhaps they are not urge killers, and kill exactly the type they want to kill? Maybe they are more selective and do a lot of homework, including calling different sex workers, and knowing many, and when the type comes, they make their move?
RH looks like a hoarder, but maybe in killing, he was more selective? Then he might end up with fewer victims.
Just a thought.