I think I have my opening scene. I haven't tried to write it out yet -- it literally came to me just as I was climbing into bed last night -- but I can see it, and if I can see it then I can usually find the words. Something like...
Darian Silver stood at the edge of the airfield and wondered if he'd just made another big mistake. On the far side of the field, a massive beast nudged against the smooth stone spire of the only dock, its fins shifting in the air as it adjusted to keep the gondola on its belly level with the upper deck. Waves of color rippled across its flesh, contrasting with the lines of the harness that held the gondola in place. It seemed far too large to be floating in the air. The mandibles at the front of its head were large enough to rip to his house apart, and body was... he thought of old man Winterwood's dry goods shop in the village, but that was too small. He didn't have anything to compare this to.
It was huge and wonderful and terrifying, and he was going to get into its gondola and let it carry him to the Academy.
His father, perhaps sensing his mood, asked, "Are you sure you want to do this?"
Darian managed not to swallow, and said: "I still don't think I have a better choice."
His father nodded at that, then reached down and clasped his shoulder. Darian adjusted his pack. He was fourteen years old and leaving home for the first time, and he didn't know whether to be excited or sad or terrified. Apparently, in the face of such uncertainty, his brain had decided to go with all three.
So that, or something very like that, will be the start. The Hero's Journey can bite me; I'm going to skip the Ordinary World and the Call To Adventure, and leap straight to the point where Darian is making a final decision about moving out into the larger world.
Also? Sleep is good. Sleep is a wonderful, wonderful thing.