When you’ve been unclear on when the delivery date is?
When everyone is working day and night to finish the task but is so far off?
When you haven’t been asking for updates and assume it’s going to be done when you were hoping it would be done?
When there are two weeks left and QA has not started?
None of these times, it should have been done months ago, when you were asking these questions, getting clarity, making sure people weren’t burning out, asking for where problems are and ensuring each group has time to complete their tasks.
That’s when you should change the Delivery Date.