My hatch early this month had 2 pips late into day 18. They started mass exodus 15 hours into day 19 and were all finished mid day 20. These eggs were collected and given to me... stored at room temp for a day plus... which that and the still air incubator could have been the reason for all being done early. Many factors influence the "when"... but that was my experience.
If the hatch is complete... they can move. They are finished incubating once they are out of the shell... dried off.. (fuzzy mode) You are recommended not to move new hatches while others are still in hatching stage. They can live a day or two just fine in the incubator, living off their absorbed yolk sac... while waiting for everyone to catch up. Hope that answers the question. Have fun