Data generation happens automatically via a cron job. By default, the cron job runs once a day at midnight. You may change the schedule by updating the scheduling property and restarting the application.
The data generation schedule can be modified to refresh multiple times per day if you would like the data to be updated more frequently. Any job that is triggered while another is already processing will wait until the first is complete to avoid any conflicts. Keep in mind that data generation can take a while as the processing time is directly correlated to the database size. If you decide to increase the frequency in which the data is generated, make sure that it is not run too often to avoid any potential performance issues.