I smoked a day before I had a swab test for a job and passed... And they were the company who does the tests so you should be fine. Also I found this...
The following chart from LabCorp gives approximate detection periods for each substance by test type.[1] The ranges depend on amount and frequency of use, metabolic rate, body mass, age, overall health, and urine pH. For ease of use, the detection times of metabolites have been incorporated into each parent drug. For example, heroin and cocaine can only be detected for a few hours after use, but their metabolites can be detected for several days in urine. In this type of situation, we will report the (longer) detection times of the metabolites.
•NOTE 1: Oral fluid or saliva testing results for the most part mimic that of blood. The only exception is THC. Oral fluid will likely detect THC from ingestion up to a maximum period of 18-24 hours