There is now a standard dimension available named "Customer Sale Type" that is available in both the Order and Product reports. This dimension can have the following values:
First-time
Returning
(no value)
Customer Sale Type derives its value from the field "Customer Order Index", which is also included in the Order and Product reports. Customer Order Index represents which sequence the order has in the customer's own order history with the shop.
If Customer Order Index has the value 1, then this means that the order is the first order placed by the customer and therefor the Customer Sale Type will be set to "First-time".
If Customer Order Index is 2 or more, then the customer is categorized as a "Returning" customer for that order.
If a Customer Order Index for some reason cannot be determined and it does not have a value, then Customer Sale Type will have no value either.