I've got some information to share about the reminder option for recurring transactions in QuickBooks Online.
At this time, being able to make a recurring transaction that sent out a reminder before sending the invoice isn't available. When setting a reminder in QBO, you'll be the one to b reminded that you have a sales transaction that needs to be sent.
However, QuickBooks integrates with various third-party applications. I recommend visiting our app site and check out for the app that supports your desired functionality.
You may also visit these links below about managing and creating recurring transactions in QBO for reference: