How to p a saliva test.?

I have an interview at krogers tomorrow, and im pretty confident that i will have the job. Unfortunately like any average 17 year old I done some partying this weekend. Actually Sunday. I ingested some majijuana, but only a small amount. I dont have time to buy anything and dont say anything on how i should stop doing drugs. I might have learned my lesson in this case. How should I go about ping this saliva test?