It appears I'm not alone with this issue, so I hope someone can help or this functionality can be added to Odoo 18 online 

I have several subscriptions for customers (like domain registrations, hosting, software maintenance, etc).  The commercial agreement with customers is that they receive invoices for upcoming subscription that need to be renewed about 6 weeks upfront.  This helps them to judge if that subscription is still needed and makes sure we don't prefinance anything.  Everybody happy ! 

There is a problem however: by doing a manual renewal or by executing an automated action, the subscriptions can be renewed whenever you like, it creates a new sales order without any issue and as expected... but that sales order cannot be invoiced unless the 'Next Invoice Date' has been reached.  So all is there in place but the last step prevents for invoicing upfront. 

I don't understand why Odoo is restricting the creation of the invoice but it makes it impossible to support the use case which appears to happen quite often.