What is your tenure with this company and what kind of hierarchy do you have in your department? When you say 'My Director' in your department, is it in HR? It also depends upon the time frame when he announced it and how it was done.
If everything went on an official basis, you should first check when your role will come into effect. If you have already moved into this function, how long have you been in this role? If you have already been introduced to the corporate team, through which authority was it done? So, it would be beneficial to calculate your time and probation—the general time-frame it takes in your company to issue a letter, the hierarchy you need to follow to approach your director, etc.
Don't jump or rush into things... good luck!