Report to compare Revenue GL Date to AR Receipt Date

The vast majority of our projects have distribution method work/work - so expenditure items are directly linked to revenue and invoices.

We would like a way to compare the date when revenue was recognized for an expenditure item, to the date when AR receives payment for the invoice it was on.

Rather like a collections aging report, but expanded to one step earlier in the process to include how long it took us to get the expenditure item onto an invoice to start the collections clock.

This seems like a pretty fundamental metric - could anyone point me to an existing report or query that others have used to do this?