I need helppp!

Alright, so i need to move my setup asap, one simple question, How long could a female plant that has about 3 weeks left go without light?

Not sure how long they can go without light, never tried. But surely if you move them during the lights out period, and if your doing 12/12, then you got 12 hours straight away without any detrimental effects. I have known people who have had to move plants before and theirs went without for nearly 24 hours and they had no problems. Just make sure when you move them they are bagged with a light proof material, reduce the risk of shock as much as possible.