i dont really know how long it would take to get all the THC out of your system but ive often been told it stays in your body for around 3 months each time you smoke a joint....but in order to cut this time ive always been told 4 things that help to clean your system out

1) a shot glass of vinegear down in one in the moring and before bed
2) eating cilantro a common garden herb that bonds with metals and toxins in the body and flushs them out through urine
3) drinking cranberry juice kicks the kidneys into over drive allowing them to flush more THC out in one go but dont drink to much over a short space of time as this can lead to kidney damage
4) THC is often sent to the tips of your hair to wait to be processed....getting a little of the top every week or so can help to make a difference