Within PSOhub, there are various moments where the smart invoices are generated. This is:
Every day at 18.00 GMT+1 / 13.00 EST
For projects that are set to active and have smart invoices with a due date of today or before today, immediate creation after setting the project to active
If you need an invoice sooner, you can use the create invoice button and check 'Manual SMART' to invoice it yourself.