Login to the Administration (ask your Prima Coordinator if you don't have access)
Click on EDC Administration
Find in the list of Processes - Financial System Export/Import
Double click into the line and click the change the Connection Type to Always On - and Save
Restart the EDC to activate the administration change
The EDC will post all completed invoices over to Sage on every run (every 30 seconds) until you change it back to Timed Execution.
Do not leave the Sage connection to Always On. Once the invoices have posted change back to Timed Execution.