Look in the old cockatiels section for more info on breeding. Lots of info there.
If you wait until the birds are two weeks old, you can pull them from the nest anf start hand feeding then. This is how many breeders manage their babies, including the breeder who raised my Senegal, the most well raised hand fed bird I have ever interacted with. I suggest you buy a book on cockatiels and read the breeding section. Then call your vet and set up a way to have hands on experience with hand feeding the day you pull the babies. By the way, you pull the chicks early in the morning, before the parents feed them so they are hungry when you introduce them to hand feeding. An inside trick breeders use I got from a book.
As I got older, I got less enamored with hand feeding as a taming method and I now use co-parenting for taming. Lots less mess, handling chicks from the age of 15 days every day. Works well for hand tame chicks who know they are birds but still like humans and seek interaction with humans regularly. But I agree hand feeding iis the best taming, imprinting methods for instantly tame pets.
Good luck and have fun!