So you have two concerns. The first is finishing that project. The second is finishing it on time. They are two closely connected, but prioritizing your concern is important for accomplishing both.
Your stress is not so much driven by your first concern but more due to your second concern. You know there's a lot left to accomplish and time is running short. If it weren't for the pressing time factor, you'd be just fine and dandy. You'd feel better about the project itself, even happy to do it. But that deadline is weighing on you; who can work with this kind of pressure?
So where do you put your focus? Do you get out your watch, set the timer on the microwave, or listen to the wall clock ticking away your much-needed work time? Do you spend time obsessing over how you could have spent your time in recent days more efficiently so that you weren't in this mess?
We've all been there, stuck facing an impossible deadline, aware of how laziness got us into this bind. College papers, high school projects, work deadlines. It's a part of our lives. We have these two closely related concerns.
The worst possible choice in this situation is to concern yourself with the time you didn't spend and the time now passing away. The worst thing you can do is to seek first to know how much time you have, or how quickly its evaporating. Spending time thinking about time is wasted time.
Instead, seek first the project and it's completion. Put your focus and energy there; stop spending your focus and energy on worry, which is draining you dry. When you put your energy into completing the project, the second problem--the issue of time--goes away. CS Lewis said the same thing, "When you put first things first, you get the second things as well. But when you focus on secondary things, you lose both."
And before him, Jesus said the same thing. That is, God was showing us what the right priorities are. God himself. "Seek the Kingdom of God above all else..." Everything else will fall into place.
And just as accomplishing the project is closely connected to meeting that deadline, seeking the Kingdom is dynamically connected with "everything else." When we focus on everything else, we are spending our focus and energy on the wrong things, the things that drain purpose and meaning from our lives. When we focus on the first things, we discover the second things are right there.
God is not one to break a promise.
It is we who are unwilling to trust him.