Hello and welcome. I was think thinking that you call dungeons what I like to call my “playground”, but I’ll go with @JGood 's fairground analogy too. It’s not often that he and I see eye.
I jest, we are “simpatico” as he once called it - we often think in similar ways 
First things first, as others have said, just relax and take your time. 18 hours seems like a long time, but remember, you likely won’t spend all that time playing - there’ll be time for talking, exploring, negotiating and aftercare too.
Secondly, you don’t need to be a “seasoned pro” - JGood and I have more than a decade (more than two, for the dino over there 
)'s worth of experience each in BDSM, but neither of us would consider ourselves “pros”. We’re both still learning and exploring, and that’s okay. Everyone starts somewhere, everyone learns, adapts and grows.
Explore, but don’t feel compelled to do everything or try things you don’t know/aren’t sure of. It’s better to go with what you know/ works for you than wind up in a precarious situation your poor partner needs the fire brigade/ medical treatment for!
Don’t forget your rules, your boundaries and your safeword - it’s a new environment, but you’re still the same people. I know how Doms are for new places with new toys: as the sub-wife who once accompanied her Dom-husband to a fire play demo and had to give it to him real why fire play might look cool, but he was absolutely not ready to try it for real? Yeah, believe me, I know all about Doms and wanting to try new things. Sometimes I think to keep a bucket of Legos on standby, but then for the sadistically-minded, that’s probably just another thing to torture us poor sub souls with
Anyway, Mr Good likes to tag me in posts and give me things to do, and he knows perfectly well how to plan a scene, so I have no doubt at all that he can help you with this one.
Have fun, Sir
Oh, and if you’re at all curious, this is my bedroom/playroom. Designed and built by yours truly 