How to care for hatching eggs
To intervene or not to intervene
If intervention is necessary as a last resort
Egg Candling Pics: Progression Though Incubation
Exotic Pet has a good reference to the draw down as how it is affected by interference: Assisting the hatch is a difficult decision, and in this author's experience, many aviculturists will do more harm than good by assisting the hatch. Normally the chick will hatch 24-48 hours after drawdown has occurred. ****By making a hole in the egg shell over the air cell, the carbon dioxide level will drop, actually slowing the hatch. ********* Making a pin-hole or opening the air cell end of the egg should only be done if the vocalization level of the hatching chick is decreasing or other signs indicating that the chick is in trouble are evident (for example, if the chick does not pip into the air cell).