Once they have externally pipped that is punched a hole on the outside they will rest for a bit sometimes a number of hours so don't worry then they should hatch pretty quickly all about the same time, if they have pipped externally and not hatched with 24 hours from the first pip then I would assume something is wrong, I have helped chicks hatch if they have not made it out after this time but if you leave it longer chances are they will die in the shell, it's not an ideal situation but the chicks I have helped in the past have been fine and grown into great adults so I don't hesitate to do it if I think they are having difficulty, trick is to start to chip the shell away very slowly where they have started after giving them at least 24 hours to do it themselves, if you see any blood stop for a couple of hours and try again, sometimes they do not making it despite our best intentions.