My bantams always hatch ahead of my full size chicks. But, I run my temps at 100.4 to 100.6. Temps that are too low, can cause the eggs to hatch late. You said floating....when chicks are fully grown, there is no room for them to move, there should be no fluid visible in there. Only the air cell with hopefully a draw down dip where they are starting to get ready to hatch.
When I said floating I was talking about in the bowl of water when water candled