...could vary either way with improper temps...at 89F the vast majority will start to pip in the 52-57d range...I personally don't know the min/max because I make sure to stay as close to 89F as possible...DAILY attention to temp, usually twice daily attention...
...when the first egg naturally pips OR at about 55-57 days I VERY CAREFULLY pip all the eggs...I use an ophthalmic suture scissor with very fine tips...express out a little egg fluid...it should be crystal-clear slightly yellow/amber in color...if it is even slightly cloudy that is NOT good...make a V-shaped flap...enlarge the flap over the next few days...the neonate will shortly expose its nose and begin air breathing...let the baby leave the egg on its own...normally-developed babies will do so...
ALL RIGHT!!!!....baby BPs!!!!
sjm