The order is so urgently required that we have to ask you to speed up shipment. If shipment is too late, we'll have to turn to other suppliers.
I am sorry, but we can't advance shipment. The manufacturers are fully committed. They have no stock on hand.
Can you find some way for an earlier delivery?
How's this then? We propose partial shipment. We can ship whatever is ready to meet your urgent need instead of waiting for the whole lot to get ready.
Sounds like a good idea.
We propose to deliver 50 % in June and the balance in Aug.