i can offer some advise on when you're pissing. DONT let it be the first piss of the day
DONT piss straight into the cup, take from midstream instead.
DONT flush afterwards, they call your test invalid and make you take another one.

maybe they will give you an oral test, oral tests are crappy, I had to take one and wasn't prepared (i had fake piss) and i had gotten stoned the night before...it didn't pick it up and i've heard similar things from other people.

Good luck!!