Hello! I remember your other thread asking about taming them.
How old are the budgies? Do you know if they are male and female? Letting two birds reproduce without proper knowledge of how to take care of babies should they need help or should the parents neglect them can be a very dangerous thing to take on. You risk much heartbreak and death by allowing them to incubate eggs and hatch them. Please reconsider breeding your budgies. Take out the nest box and allow them to just be birds. They can still live a happy, healthy life without reproducing.
Just a side note, they may mate, or maybe already are, and any eggs laid should be picked up and shaken to destroy the yolk inside and then take away all the eggs when the two lose interest.
Again, please reconsider letting your birds hatch babies. Why don't you focus on earning their trust and training them?