After you register your camera in relation to the recent Service Advisory, you will need to wait up to 3 weeks for the Service Centre to send you another email with notification that we are ready to repair your D750, containing the postage label. This delay is due to spare part availability and increased workload of the service centre. Then the repair itself will take another 2 weeks.
Please note that the repair can be performed at any time, even out of warranty, if it is not convenient for you to send it in at the moment - the postage label does not expire.