To have an Invoice automatically get created after the Timesheet has been Online Validated by the Agency the settings need to be changed to Every Timesheet for both the Billing Cycle and Invoice Grouping Under. This means the Invoice will move straight to the 'Undelivered Invoice' section.
This setting can be done under the 'Client Entry' (Reference Data)
The Invoice creation part of the Client Entry set up under the fields 'Billing Cycle' select "Every Timesheet" button
Then for the 'Invoice Grouping' also need to select the button of "Every Timesheet"