Are you young and active? I'm neither young nor active, so my results were 30+ days and still dirty so I subbed with QF, although I might've been able to dilute.

If you got 20 days, then order those cheap thc test devices online - either Ebay or google it (I got mine for under $2 a piece - ordered 10). Test your first urine of the morning and then test after some dilution. If you can pass your first void of the day, you are ok. By taking the tests you will know better about what your options are.

Read the posts from the others and read the sub and dilution sticky.

Good luck!