I've used my incubator twice: the first time was with bantam sultans, the second was with the guineas. If I remember right, I had early hatches both times, which I attribute to the incubator ... there's really no room for human error as it controls temp, humidity, egg spin, etc.
The guineas were fast hatchers. I went to Lowe's and came home to find two had hatched, so the time from initial zip of the shell to being fully hatched must've been less than an hour. They are hardy little things, like wildcats.
Although mine were never friendly, I still enjoyed watching them "do their thing." They have big personalities, and I'd gotten so used to chickens that the guineas were a real treat to watch. They reminded me of dogs, the way sometimes if you put some strange object in the middle of the floor, your dog might be scared of it for a minute and walk around checking it out before getting close enough to sniff? That's the way the guineas were with everything in the yard if I moved it. If I happened to be sitting outside one day and moved a chair, the next time the guineas saw it, they'd be all angry that it was "in their space."
It sounds like you're doing your homework, and I wish you well with them. I really did enjoy them, and would consider having them again but possibly trying to clip their flight feathers to prevent an escape. Like someone else said, though, they were very fond of perching in the trees, which was always a cool sight.