Hi,
The best thing to do is leave them alone, give them plenty of privacy, and hope they figure things out. Most first clutches fail due to parent error. But if they don’t learn, they will never be good breeders. I do not recommend artificial incubation. Cockatiels are almost impossible to keep alive from day 1. It is a round the clock job to hand feed them, and most of the time they seem to be doing well and then die. They really need the parents to get them started off. Let the pair learn, and likely mess up, and then once the eggs are past due, or hatch or if you have chicks, once they leave the box, you need to remove the nest box and rest the parents for 6 months. You need to do this after each clutch whether the eggs hatch or not. Never leave the nest box up year round. If they fail with the 2nd or even 3rd try, then the pair probably isn’t cut out for breeding. Some birds simply are not good parents.
It is important that you are feeding them a nutritionally balanced diet such as pellets – they will not get the nutrition they need on a seed diet. They also need leafy greens and chopped veggies. And right now they need a daily egg food – this can be a commercial dry egg food or you can cook an egg with the shell washed, crushed and cooked with the egg. Off this daily from the time you give them the nest box until they are done with the eggs or until any chicks are weaned. Breeding birds will go through a lot of food, and if the eggs hatch, you will need to replenish the food throughout the day. If the parents do not have the nutrition they need, or feel they don’t have plenty of food, they may stop feeding their chicks.
Thank you for asking Lafeber,
Brenda