You’ll likely be asked to get a drug screen done right when you get a job offer, but your offer will be contingent on the drug screen. This is generally how pre-employment drug screening works. So as soon as you get a job offer, you’ll be asked to get a screen done, and you can go to an urgent care clinic for immediate, on-the-spot screening. After your screen, you’ll take the results back to your employer and they’ll decide how to proceed.