Does anybody know which date-fields LN uses for the calculation of the delivery time rating (tdpur8106m000), e.g. planned receipt date or confirmed receipt date to actual receipt date or transaction date of receipt?

regards

The confirmed date is used. In fact tdpur451.ddtb is used. This field is initially equal to the planned receipt date. At moment of entering the confirmed date the 'current planned receipt date' (tdpur451.ddtb) is updated.