What can a job tell you?

Okay, so how soon after applying for a job will you know if they drug test, aside from if they put it on the job-ad.

One job I looked at said "this is a drug-free environment", which obvi means no drugs... another said a requirement was submitting for drug testing... But if it's not on the job-ad, can they still make you do one?

And if they do make you do one, how much time in advance do I get to know this? I mean they can't be like "okay we'll do your interview on Friday" and then Friday comes and they're like "okay now pee in this cup".

What can I expect?

You could be subject to a UA right after the interview. Every company is different but I would prepare yourself for the worst possible scenario. There is really no way to know unless you know someone that works there. If your not willing to abstain and piss clean then get yourself some Quick Fix and sub. Most pre-employment UA's are not observed so it will be a breeze.

I just had an interview and to my surprise I got a saliva test during the interview I was told to stick a salty little stick in my mouth for the duration of about a minute as I proceeded to tell her I'm a medical marijuana patient...

In this day and age I think you have to be prepared for pre-emplyement and random UA's. And some places are trying alternatives to urine tests. So people need to educate themselves about the different systems and be ready. Saliva tests are easily beat if your prepared, even hair and blood tests can be beat. But you gotta be prepared.