On the Credit tab of the Customer window, you will notice a field called “Collection trend (days).” This field is designed to display how much time, in days, exists between an invoice date and the date the payment was collected for that invoice. This field will list each invoice to payment difference separated by commas, listed oldest (invoice date) to newest.
In the screenshot below, notice the Collection trend (by days) field. For customer Ruby Baker, it seems that the collections took 144, 77 and 7 days between the time an invoice was posted and when a payment was collected for that invoice.
In the next screenshot, notice the Invoices tab for the same customer. You can see the date related to both the Invoices as well as the Payments. using the amounts, we can tell which Check was associated with which Invoice. The green invoice has a date of 10/6/2015 and the payment seems to have posted on 2/23/2016, a difference of 140 days. The purple invoice has a date of 12/8/2015 with a payment on 2/23/2016, a difference of 77 days. The yellow invoice has a date of 2/16/2016 with a payment on 2/23/2016, a difference of 7 days.