How long does it take for your cycle to start if your off the shot completely?

It has been said that you can pretty much instantly lose your periods while other women had their period for up to a year of being on the shot. I'm on month two and no longer have my periods. It has been said that you can pretty much instantly lose your periods while other women had their period for up to a year of being on the shot. I'm on month two and no longer have my periods.