Former All Black Williams and ex-Wallaby James O'Connor were set to front the Ligue Nationale de Rugby's discipline and rules commission on March 29.
But that has now been postponed until April 12, reportedly on their request.
Williams is still to appear in court over a charge of allegedly buying cocaine, after he and O'Connor were arrested by Paris police in late February.
O'Connor has already been fined for possession of the drug.
