It could potentially appear on a background check at any time.  Whether or not it will appear depends on how good the arresting agency is at reporting arrests and the resources used by the company conducting the background check.Many arresting agency now have online access to their arrest records which are updated daily to show who is in jail and who is not.  Others will also sell regular updates to companies who compile information for background checks.  If the agency is current on their reporting practices, arrest data could have been available on day two to the public.  If the agency is limited on resources, technology, and manpower, then they may not be current on reporting-- which means that no one would have access to it.Companies that perform background checks collect data in a couple of different ways.  Some purchase it in bulk through open records requests from agencies and court clerks.  Others use runners to make specific requests on specific individuals.  And still others may use a combination of both.  The quality of the background check will depend on the tenacity of the company that is compiling the data.If you really want to know what will show up on a report, do some research on the companies your are thinking about applying to.  You can then purchase your own report from the company who does their background checks.  From there, you will know exactly what is being said about you on the report.