It says underneath 'If a new order is made, or orders cancelled, the slots will move. The manufacturer will also remove all empty slots before the production of each aircraft begins'
I don't understand your reply - sorry. I'm not bothered about using the production slot for myself, as you can see from the screen shot I already have orders. I know I can't jump the queue, but that doesn't explain why the production dates have not shifted forward to fill the gap.