HELP Drug Test this Saturday at CVS HELP

So I got offered a cashier position at a brand new CVS that is opening this weekend. The first email I got from them said "drug screening" so I assumed that they would ask for one when I went in for orientation, but they have not said anything about it since they scheduled me and I even asked what to expect and they said nothing about a drug test. I have all my paper work turned in too and they already did a background check on me.
\nI already had a plan to use my older sister's piss. I bought the synthetic urine kit and got rid of the contents because I don't trust it. I was gonna use the bottle to keep track of the temp. I've been practicing. I've been able to keep it at about 94-98 degrees for about an hour in my underwear (kinda just tuck it in there as if I was wearing a maxi-pad). Mind you, this is my first time ever doing this but I'm fairly confident and I haven't smoked in about a week or two and detox is not an option because I don't have a very fast metabolism to burn it all out or just get it out of my system.
\nI guess this is my dilemma. I was supposed to have orientation tomorrow, but they moved me to Saturday because of my school schedule. They just told me that I was going to be doing an "8 hour shift" at orientation (it'll be a different store, not the one I'm going to be working at) so that I get proper training. I start at 9 or 10 am on Saturday and I'm kinda questioning if they're even going to test me or not now. They said "shift" y'know as if I already have the job and they said they were gonna order my shirt. I'm not sure whether I should take the piss anyway and just have a hand warmer near my crotch the whole time because I won't know when they make me take it (if they do) or whether I should assume they weren't going to drug test me.
\nAny ideas?