Is it permissible in Sharia to marry a girl who has not reached the legal age for marriage, in preparation for administratively completing the contract upon her reaching the legal age?

It is permissible to marry a girl and عقد (perform the marriage contract) with her, with the permission of her guardian and the presence of witnesses. By doing so, she becomes a wife from whom a husband is permitted what is permissible from his wife. However, if she is young, it is not permissible to consummate the marriage until she is able to bear intercourse. Delaying the documentation of the contract does not affect its validity.