i don't have first time hand expereince on these situation. but from all the research i have done
1. drinking tons of water wont help just staying hydrated is enough..dilute on test day ..refer to dilutiion thread
2. exercise and increase fiber intake (metamucil, benefiber) but to not diet...exercise a lot till Saturday. if u can burn 1000 calories a day
3. start eating a lot of fatty foods/high calorie on saturday to slow down metabolism and don't be active.not sure on this but there is also a possibility this can cause a reverse effect of increasing metabolism(any one confirm?). u may want to start eating red meat to increase creatine if u want dilute.
4. this part will probably cost u some money 15 plus dollar eac h if u cant get it from online. but take a at home drug test on monday with ur first piss, if u pass that ur good. if not and there is some how you can get money get a second at home test, perform a dilution and see if u can pass the in home test if u pass then u no what u have to do on test date.
if u smoked more than once a week for a month ur probably in trouble

detox drink have the same effect of drinking a lot water. so u dont want to waste ur money on that.
ur best option if u know someone u can give u a clean sample..then try substitution..get a travel shampoo bottles from rite aid or walgreen 2 dollars..some drug test come with the temp strip on the cup peel it off and put it on the shampoo bottles so u can keep track of the temp on urine...u may want to skip all of the exercise and go straight for substitution. if this test means a lot to u can manage to get some money for sub and skip the at home drug test.

Do some research on detection times see what fits ur case.