The harsh reality of life, of the book writing life, is that many of us do not have a clear idea of our book’s endings or if we do, the characters do something that changes said ending. This creates the need for necessary changes during the editing process.
So why must you specifically focus on the first chapter?
The two must be mirror images of each other. It doesn’t matter if you have crafted the world’s best opening paragraph and the entire chapter sings with enchanted prose, if it does not create a duet, you’re in trouble.
When you come to the end of a first draft, you know the characters better. You understand that they have handled situations differently than you thought they would. They are no longer the same people that you created in chapter one, and sometimes they are going in completely different directions.
For the sake of your readers, scrap chapter one. Read through your manuscript as though you were one of your readers, don’t take any notes. After you have finished, go back and read both the first and last chapters. These should be able to stand on their own. Is the prose similar? Is your protagonist facing the same kind of choices? Is his final victory reflected in chapter one?
If you can’t bring yourself to scrap the entire chapter (its not as bad as you’d think, trust me) then do this little exercise: write 3-4 different opening paragraphs. Push yourself. Try setting the scene differently. I went through four different settings for The Clouds Aren’t White and then changed again after the book was finished, because my protagonist and the plot were screaming for it.
So, give up on the first draft. Recreate your world and let the beauty of your writing shine.