How to set Sales Invoice before start of Subscription period?

I’m trying to understand the date behaviour in Subscription and Sales Invoice (cmiiw):

  • the Sales Invoice (SI) due date is calculated to be the same as the subscription end date.
  • even if the Generate Invoice At Beginning Of Period is set, the days until due is still calculated based on end date.

Example:

  • Subscription (e.g. for a monthly plan):
    • Start date: 6 May 2022
    • End Date: 5 June 2022 (start date + 1 month)
    • Days Until Due: 0

This subscription will create Sales Invoice as below:

  • Sales Invoice:
    • Date: 6 May 2022 (the same as subscription start date)
    • Payment Due Date: 5 June 2022

Now, if I set the Days Until Due to -7 (due 7 days before the calculated end date) then the Sales Invoice will be:

  • Sales Invoice:
    • Date: 6 May 2022 (the same as subscription start date)
    • Payment Due Date: 29 May 2022

The scenario I aim:

  • The invoice is generated and sent 7 days before the next period start.
  • User has grace period time to pay 14 days (meaning 7 days before and 7 days after the next period start)

My questions:

  1. How to generate the invoice before the Start date? (this is to set the invoice date 7 days before the start date)
  2. How to set the Payment Due based on Invoice Date? (this is to set the grace period user must pay 7 days after the start date).

I hope I make my questions clear.
Thank you

Does anyone do similar to this?
Can anyone please guide me how to set it up?
Thank you