How do I know when the last sync has occurred?

Working from Billings Pro on Mac, you can view the following details:

To view this information, go to the File menu. Under Sync with Server, there is a menu item saying "Last sync:" which displays when the last sync has occurred. There is another menu item saying "Last sync with changes:" which shows you when the last sync with actual changes has occurred.

See also

About Billings Pro

Synchronizing Billings Pro