How to pass a urine drug test 😬?

I don't smoke a lot. Maybe 2 or 3 times a year, i'll smoke weed.  Last time I smoked, was July 21st. I have a drug test TOMORROW (Surprise!) So, I'm worried about what if i don't pass . I been drinking a lot of water & my boyfriend gave me activated charcoal yesterday to clean out my digestive system , I dont think it would work but it's worth a try. What else can I do? Any advice? No rude comments please. I smoked before i even thought i would get an interview and I didn't expect it to happen because I was just doubtful about it. Thanks!