Make sure your products are configured so that their Sales account is set to one of your deferred revenue accounts. This will ensure that when you create a new invoice, all of the revenue for those products is recorded in the deferred revenue account rather than a revenue or income account. ProRata then handles the monthly journal entries to decrease deferred revenue and increase revenue.

If you do not already have one, create a Deferred Revenue account (Liability).

Perform any "clean up" prior to importing your data into ProRata. This includes editing prior invoices tracking categories and products.

ProRata will not allow you to import "tracked items" you have in Xero.