Here is a few details on how frequently this happens.
Full synchronization between HandiFox and QuickBooks Online takes place hourly. The frequency can be changed in the Settings section on handifox.online.
New data created in Handifox is uploaded to QuickBooks straight away. Some information (Products, Customers, sales transactions) is downloaded from QuickBooks right away after it is created or updated (in most cases the delay is within 5 minutes).
The user can force a synchronization in the web app by clicking QuckBooks icon . Synchronization automatically starts when a mobile device is being synchronized. To make synchronization of the device faster, you can uncheck "Force data loading from QuickBooks" on the Synchronization screen in the mobile app.