An employment background check should take between 24 to 48 hours after you've submitted your application and they have had time to get your application reviewed.
Sometimes it can take as long as a week or even 2 weeks to hear back from a potential employer about a job you've applied too.
But if you don't hear back within a week it would be a good idea to call the job and ask about the application because that shows you're really wanting the job and can help you get hired.
Also apply for other jobs while waiting to hear back from that job because you might not land that job and may land another job.
Sometimes it takes as many as 100 job applications before you get hired to one job so don't give up.
When I applied for a job the background check took 48 hours and then I heard back from the employer and got the job.
But it can vary from employer to employer and how many other applications are ahead of yours.