Buttons will hatch day 16 to 19. You never know exactly when. Quail don't always hatch on a certain day like chickens. I've had a late hatch when my temps were high all incubation and an early hatch when I thought for sure they'd be late. You just have to wait.
I've never seen any of my quail eggs wiggle or even make a peep. They sit there frustratingly silent all day long. Then suddenly when I'm not looking a quail pops out. Seriously sometimes they just appear. I checked the bator, saw nothing, sat down at my computer, and then wondered why my dog was sniffing the bator less than 10mins later. Look in and there's a little button chick racing about.