Deprovera

I had been on the shot for abouttwo and a half years. I gained some wt. Which was fine because i was underweight to begin with. No other side effects good or bad and i enjoyed not having periods since they were very heavy before i started the shot. Istopprd taking the shot a few months ago to give my system a break but now i want to start back up. I cant remember when, during my cycle, that i start up again with the first injection. Do you know?