I did the first heating and drying cycle in the furnace. As I understand it, it’s best to slowly heat and cool the furnace a few times to fully dry the refractory lining, so it doesn’t crack. I started on this today by burning some newspaper and wood, then adding some charcoal. It’s been burning for about three hours now, but mostly just simmering in ash.
Here’s a video of right after I got the fire going…