This is our rules:
* #1 Don't get impatient.
* Don't mess with the pipped ones for at least 24 hours. They usually rest for a day or so after struggling to make that first pip.
* Wait on the 3 with no pips at least 24 hours then check for pips
* If no pips after 24 hours, candle the eggs. Watch for movement, listen for peeps/tapping and check for rotten eggs.
* Helping them hatch is a VERY risky thing to do and we've found that doing so endangers the hatchlings a lot more times then it helps. They have to separate from the membrane and absorb the yolk. Helping hatching can interfere with these processes and kill the duckling.
* Being inexperienced, it's best to just lest nature take it's course in the vast majority of cases. I'd only help if your humidity is very low, the duckling is mostly out and parts of the shell is sticking to the duckling and then only the "cap". Let the ducklings do the rest by themselves.