Unforuntely there's really no time table on when it will come back. I read on Upjohn's website it could take up to a year for the depo to leave your system. I have been on since Nov. of 2003 and had my last shot on Dec. 15th of 2004. About to two weeks ago I spotted very little for a couple of days. I was suppose to have a shot on March 4th but decide not to cause of the side effects I was having,and had the Paragard IUD put in on this past Tues. I started spotting on Thursday and it been heavy bleeding since than. I suggest maybe seeing your doctor to make sure that your hormones are in balance and maybe go on the pill to kick start your period again. Good luck.