The dimension Customer Order Index is the position of the current order within the customer's order history (a 1 here indicates that it's the customers first order). With it we can create the metrics First Time Customer and Returning Customer. Below is two screenshots that shows you how to to it.
First time Customer
If Customer Order Index is missing values
We have seen that some orders have no value on this dimension. One reason for this is that orders that are not made on the web shop (e.g. through a physical store, a subscription app or by phone) does not get a value in the field. Reach out to us if you are missing values and we will have a look!