test in a week

I just got offered a job making a decent salary as a mechanic. I am also an Ulcerative Colitis Patient. I've been smoking every day, about two to three joints, for years. I smoke mainly because i like to but it helps a lot with my condition. I have until May 2 at the longest to take the job, i'd like to start sooner say the 25th of this month.

I am 28 years old about 165lbs, 5'9"

I plan to drink plenty of water and cranberry juice for the next few days hoping that will clean me up. I bought a 16 oz bottle of QCarbo fast cleansing with elimenex for the day of the test. I also plan to take about four aspirin that morning, and keep up with the water and juice. Everyday, for about three months now, i've been taking a multivitamin (Centrum Performance), Barefoot Coral Calcium Plus, and Pro-Biotics. These pills i take for my condition. I also have self test kits at home and i plan on testing myself before i leave for the test.

what are my chances of passing the test. I believe it will be a urine test but i don't know if it will be supervised or not. any other advice or tips would be greatly appreciated.

BTW: about two months ago i tapered myself off of prescription steroids ( Prednizone) which i took for about a month. I was also taking Asacol as prescribed by my doctor. I plan on mentioning this when i go for the test, any ideas what effect these medications will have on the test?

From what i've been reading i should be okay, but i'll know before i go. haven't been eating much, is this a good idea? i've read differing opinions on the eating thing. I'll post back if i pass/fail. drinking about 2 liters of water and a liter of cranberry juice a day until test. should i up the amount of either?