In the early years, I, like many apprentice writers, felt that I had to write a novel in the same way I read it: starting with chapter one and working chapter by chapter through the project. Generally, I got to chapter three before the project failed, because, of course, writing doesn’t work like this. The process of writing is much more like putting together an elaborate jigsaw puzzle where all the building blocks of fiction are moved around repeatedly as the project builds. For example, the ending in my literary novel Turtle Valley was once in the middle of the book.
 
So, you can’t come into a project thinking you’ll know what you’ll end up with. Your project will, and should, continue to surprise you as you write and rewrite it. Writing is an act of discovery.
 
In the discovery draft, I write in terms of "scene" rather than "chapter" because I know the scenes will shuffle around like cards in a deck and I won't know where they will fall. In fact, as I'm writing, I'll leave gaps in my writing with placeholder instructions in bold letters that say DESCRIPTION or TRANSITION. After I've decided on my situation and characters, I focus on the nuts and bolts of scene: dialogue and action. I leave all else for later. That makes it easier to shift stuff around.
 
So, as you start to write your project, just sit down and write a basic scene (action and dialogue). Then write another, and another. The writer Gregory Dunne said, “Writing is like a manual labour of the mind; a job, like laying a pipe.” And I agree. You lay one pipe (or scene) after another. Eventually it all comes together. Those blocks of exposition, description and transition are the fittings that fit those pipes (scenes) together.
 
I will write bits of description and transition as well in the first draft. But I often keep these building blocks in a separate file. I'll retrieve them when I'm starting to fit the scenes together into chapters or a story and I have a better idea of where the scenes will fall, when things are starting to gel. But I know even then that I will continue to move things around well into the editing stage.

In other words, as writers, we must learn to be flexible, to let go.
 
It's useful to think of writing fiction as if it is a magic jigsaw puzzle that can be put together in an infinite number of ways. You are free, then, to rethink situation and throw everything up in the air and start again if you need to. I do just that many times in the course of writing a story or novel.