Let's say that you are writing a novel whose narrative is non-linear. That means that when Chapter One refers to the present time, e.g. the 2010s, Chapter Two, instead of telling what happened right after Chapter One, refers to the past, e.g. the 1950s. And this structure goes on and on through the chapters.
My question is what to write first. Let's assume that it's about a novel with three different stories, but somehow related to one another, more or less. Chapters One, Five, and Eighteen describe the first story, the same thing happens to the other stories.
In your opinion, what is the most effective way to write a well-balanced/structured novel yet nonlinear: to write the first story in its whole, and then break it up in small chapters, or to write a section of the first story in the first chapter, and in the second (chapter) to write a section of the second story, etc.
This question may be opinion-based, but I think it will help me understand how writers work, and be influenced by them.