it depends on many factors (metabolism, body fat, exercise routine, when last toked, etc) but at this late stage you're only sure way to pass is substitution, either fresh or freeze-dried synthetic. a condom full of a non-using friend's urine taped to you thigh will do the trick provided you're not watched when giving your sample...(note*...it doesn't take a lot of urine so condom does not need to be totally filled, just for clarification.

good luck...and plan ahead if you can...iow, practice if using the substitution technique.