You can let your company to automatically update every day, your data will then be automatically updated from your accounting system once every 24 hours before 8 am AEST.
However, if you made changes within the source, you don't need to wait for the next day to update your data in Fathom, instead, you can go to the company's step 1 and initiate a manual update by clicking the 'Update from Xero/QBO/MYOB' button.