Employment Drug Tests

I am starting my first real job on Monday October 2nd. I have done all the interviewing and signed the final offer letter. MY company has not said anything to me about a drug test. I have smoked the past week. What are the chances they are going to give me a drug test my first day of work? I mean i am already hired so why would they wait to do it until I actually start? If anyone has any thoughts please post them. I am trying to be careful and have done two niocin flushes(painfull) and have bought a drink but I feel i am freaking my self out and have nothing to worry about.

Normally they have to tell you if you are going to be drug tested. If they haven't mentioned anything about random testing while you're working, then you should be fine. But I got a "random test" after I was hired, but before I started working...bullshit. :(

Didn't take it, so they wouldn't let me work for them.

Better safe than sorry man, lay off for a bit until you're sure.