No Title
You should notify them ASAP, by FAX and follow-up E-mail. If this is a dire situation, then OK, but otherwise you\'re asking for unnecessary potential complications and uncertainties if your request is simply because of a matter of travel convenience.
Unless you\'re looking for a postponement of only a couple of days (i.e. still April), you will not get a new appoinment until June at the earliest. The consulate must request a new visa number for you and like your original timeline for your current appointment they must do this by the 20th of the month for appointments two calendar months later.