How long does it take Walmart to contact you with the results of a pre emploment escreen drug test?

I interviewed for Overnight Stocker and was offered the job, the next day i took a drug test which was an escreen ecup drug test that is supost to be FAST. My question is how long will it take for them to contact me with results? would it be only at night via the night manager since its a night position and hes the one who interveiwed me therefor he'd be the one to tell me when the orientation was? Also would they wait for both the drug test AND background check before contacting me?? Please help im just nervous as to why its taking so long i really need this job and am a lil worried about the background check even tho i was as honest as i could be