Convert Invoice to Recurring Invoice

I use Recurring Invoices a lot but the initial invoice is usually different because of initial set up costs that don't occur in subsequent invoices. At the moment I have to create the initial invoice and then create one almost exactly the same, just without one or two items. It would be helpful to be able to convert an Invoice that has already been created into a Recurring Invoice. I can then edit it and remove any items it doesn't need.