Vendor purchase orders with delayed delivery windows

Hi there, we have received 8 Amazon Vendor orders today with delivery windows that don’t start until between Sep and December this year. We’ve never received an order with a delivery window that doesn’t start immediately - has anyone else experienced this - I have queried it in Case Log and just been told there is nothing wrong with the Purchase orders. Surely we aren’t expected to confirm an order now and then not deliver it for 5 months?