Cockatiel normally lays from 3 to 8 eggs per clutch depending on the age maturity of the birds in the wild. We really don’t know how many of these lives through weaning in the wild, but in captivity very few could raise 4 to 10 babies to fledging/weaning.
Clutches and Incubation
Cockatiels in captivity generally lay between 3 and 9 eggs per clutch with the average being around 4 to 5 per clutch. The incubation period starts when the hen or pair start sitting on the eggs constantly. Some hens may wait until the 3rd egg to begin the incubation process, so all eggs will hatch close to the same time mostly.
Generally, though, the hen will start incubating the eggs by the time she lays the 2nd or 3rd egg. The normal incubation period is 18 and 21 days. The male and female generally take turns sitting on the eggs and do this in shifts. Some pairs will divide the eggs and each sit on half of them incubate both. They will also share the responsibility for feeding the chicks.
Eggs will generally hatch every other day. From my observations, mostly the eggs generally hatch in the early morning hours.