As you consider when to write, it is also critical to consider the issue of where to write. Not only does this depend on your circumstances, but also on your personality.
While writing is often a solitary process, some prefer to do so in the company of others. They may opt to write amid the activity of family life. Their where is the kitchen table or even the living room with TV blaring. Still others view the local coffee shop as their office of choice, making a morning commute, ordering their preferred java concoction, and remaining for several hours as they pound out their prose on laptop computer. I’ve heard of entire books being written in these settings. In these cases, while composing remains a singular effort, it is happily and effectively done in the presence of others.
The majority, I suspect, require quiet in order to write rightly. The presence of others serves only to stymie their creative flow and production efficacy. They need a place to write with minimal distractions and no interruptions. While some enjoy background music, others prefer absolute silence. For all these folks, a dedicated space – preferably a private room – is a necessity. If others are present during writing time, they need to not interrupt and to respect the privacy of the writing sanctuary.
In making these determinations, sometimes the question of where needs to be ascertained before the when. For example, writing at a coffee house is incompatible with middle-of-the-night inspiration.
(I prefer to write in solitude; coffee shops, the kitchen table, and the living room are out. It took a while to find the right spot, but I ended up taking over a spare bedroom, sufficiently isolated from the rest of the house. While not quite spartan in its furnishings, it definitely has a minimalist feel to it. There is no phone or means for music, the clock is not readily visible, and the lone wall decoration declares “writer at work.” It is my writing refuge.)