Deadlines are important, but not always for the reason that most people think. When the task is a well-defined action and the time required can be easily calculated then you base the calculation on when you start.
But for bigger business decisions deadlines are not set, they are imposed by forces outside your control. And the deadline is not when a task should be completed but when a decision should be made. In that situation the only solution is to start now, because the longer you think about it, the better your decision is likely to be.
But you need to structure the thought process, make sure to sketch out what the key variables are and how they influence your business decision. Define what you know and what you don’t know. This gives you information gathering tasks to complete. Once you have enough data you organize it and then it is time for the magic to begin.
The ultimate processing device brain will start to iterate the problem. But it is difficult to predict how long it will take for the final decision to appear. Expect the provisional decision to oscillate during the thought process, but for the range to get tighter.
Hopefully you will get a moment of clarity before the deadline is up. But even if you have to settle for a preliminary decision it will surely be more accurate than if you had left it to the last minute.
Encourage your team to work the same way. Leave the big decisions as late as you can but start thinking about them as early as possible. Do the groundwork now and then give your mind the time it needs to work through them. In the downtime this implies do the small, process-orientated tasks or even better some skills sharpening to make your decision-making process even more accurate.