A coconut is not an appropriate nest for budgies, and should never be included in a cage. It will eventually be too small for the chicks and they are not easy to clean and keep sanitary.
Have you bred budgies before? Breeding should never be entered into lightly, or when you are unprepared (like you are now). There are so many things that can go wrong, it can be heartbreaking.
Do you have homes lined up for any potential chicks?
Were your parent birds vet checked before allowing them to mate?
What diet are they on?
Do you have an avian vet nearby in case of emergencies?
Do you have $$$$ set aside in case of a vet visit?
Do you have additional cages available for weaning?
Do you have another additional cage to remove mom so she doesn't double clutch?