Hi Radha,
In the wild, things are a lot different than for captive birds. The first couple of years, cockatiels have a lot more to worry about than breeding. They are learning how to find food and how to survive. They spend more time with the parents than captive raised cockatiels are allowed. The parents will supplement their feeding, teach then to forage, how to avoid predators and how to survive alone. When breeding season arrives the next year, the juvenile cockatiels will live in a flock and the parents leave to breed again. The juveniles will use this time to interact while they continue to mature. They probably will not choose a mate for another year. You also have to remember that breeding season in the wild is only one time per year. During this time the weather is warmer, the days are longer, and food is very abundant. These factors trigger hormones in the mature wild cockatiels and the breeding pairs separate from the main flocks and each establishes a territory and builds a nest. The grown offspring will no longer be welcome and will be driven away by the parents or any other mature cockatiels. They have no use for younger birds. Their focus is breeding. Then, when the chicks fledge, the seasons change signaling the end of breeding season until the next year. Then the cycle continues of training the youngsters so that they can survive on their own by the next year when breeding season arrives again.
I’m not aware of any school curriculum for bird training. There are different methods and philosophies. The most natural approach is to understand that all pet bird behavior is related to their wild instincts. So once you have a better understanding of wild parrot behavior, you can understand your bird. We do have really good training and behavior pages, free weekly pet bird webinars, and Lafeber Home Learning. These can be found using the links here:
Caring For Your Bird
https://lafeber.com/pet-birds/category/webinar/
Thank you for asking Lafeber,
Brenda