Advice: Started a new job.

My wife has been smoking for 3+ years with the same exact policy you have. Base your decision on what you can afford to lose and if you see any other employees drug tested. A week is not nearly enough time to see the trend. My wife's work tests someone most every month and fires any that violate. It's not random at her work either. These people are going to work high or smoking pot on break, you know, idiots. My wife does not worry at all since she only smokes at home (only after work) and nobody knows she does. That's the key. Nobody knows. Plus the fact she could lose her job and we would still be fine.....

Base your choice on what you know about your workplace. Nobody can tell you it's ok to smoke because nobody knows your exact situation.

However, since you have kindly asked for advice I would say wait it out a little longer and see, I doubt you would get caught unless you are actually high at work. I can tell you this. Don't ask questions about drug tests (very suspicious) and never tell anyone you work with you smoke or even support smoking. These are the number one reasons people get caught in jobs that rather look the other way like your job and my wife's.