All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There is no blame on the child for delaying the matter of informing his parents of his marriage, especially if there is a legitimate need and benefit in doing so. However, if there is no need, it is more appropriate for him to inform them as a way of being kind and dutiful to them, and so that they will share the joy of his marriage with him. This is also, in order to avoid the bad consequences that may result from concealing the matter from them, such as them becoming angry with him, and the like.
There is nothing wrong with having an agreement between him and the wife and her family to postpone the consummation of the marriage until he is able to inform his parents.
Allah knows best.