The staggered hatch is probably because the other hen was laying eggs in the nest after your mama went broody. If she hasn't had any hatch in the last two days I would take he eggs and candle them to see if any are still viable- look for movement or peeping in the eggs. I am surprised that she hasn't left the nest yet with her first hatched babies. My broodies always left the nest after the 3rd day. The oldest baby will need food and water by now. make sure you have some supplied for it, and that they are eating and drinking.
