Hello Sheila
I tried to call the council about the ceremony, but I did not get any help, al time the same generic reply: WAIT FOR THE CEREMONY INVITATION FROM DIBP, WE CA NOT HELP YOU ANY MORE.
But I mus tell that when I first was assigned with the test date it was 19/06/2017 , but I rescheduled it online to 10/03/2017 , only Melbourne applicants can change the test date online,,,,
Good luck