Drug test for new job, help?

Don't laugh alright? I was at a party about a month and a half ago and this guy I knew kept telling me I should try his weed, so I did after he'd been pressuring for a while and I have no experience or knowledge of how long it stays in your system, etc. I'd never done it before and it was one hit, and I have a drug test tomorrow for my new job. I'm 125 lbs and 5'8. Will I pass? And no telling me that I shouldn't have please, I'm already beating myself up about it, no need to preach...