Making the costume or approval after application? I made my costume over about 13 months, and once I applied I was approved in a couple of weeks. Fett is very detailed so it takes a while for them to check everything.
it depends how keen you are and deep your pockets are . I am just about finished building my ESB Fett and at the present moment I am on target to make my 12 month deadline . I decided to build a Fett mid December last year after attending a Star Wars conference in Manchester England last year.