Until the specific tyre type part of the OEM is registered in EPREL, the vehicle supplier cannot access the information related to the tyre type. Thus, the information can be updated only after the tyre supplier has registered the tyres in EPREL. Therefore, there is no alternative than showing the previous label.
Moreover the new label classes do not change between the old and the new label (apart from a downscaling of of classes E and F to eliminate the empty D class), consequently the new label is not going to change the customer purchase choice.
Disclaimer: Please note that the European Commission cannot provide a legally binding interpretation of the EU legislation, as this is the sole competence of the European Court of Justice. Any remarks from the European Commission services are without prejudice to the position the Commission might take should related cases arise in a procedure before the Court of Justice.