...to write a novel?
It's a loaded question, because it depends on what you mean; if you're asking how long does it take to put 80-90k words on the screen that's one question, but that's not the whole picture.
I thought it would be interesting to discuss the whole process, well at least my process because all writers are different. Before I write a single word I need to have an idea, luckily for me I have plenty of those, there's always a new one raring to go, even then I might like to sit with that idea for a few days or weeks to make sure it's something I think has novel potential.
Let's say I've got my idea I'm ready to go. I generally have a very, very basic outline at this stage it will usually contain 4-6 bullet points, the rest I make up as I go along. When I had a day job getting the first draft completed took about 9-12 months, (now it's 3-6 months) and at that point people might think I've done it, I've written a novel and technically that's true, but it's not good to go yet.
I'll set that first draft aside for 4 weeks and in that time I'll work on something else. Then when it's sat for a while and I've got a little bit of distance from it, the second draft will begin. This not only involves a re-read and a re-write but I also do a full chapter break down at this point to make sure I pick up any inconsistencies and plot holes. This process takes 4-8 weeks, depending on how good the first draft was.
But wait there's more...next I'll send this to my editor, he'll go through it all and come back to me with story points and anything that needs work and has a work over of my grammar and spelling. This bit takes 4-8 weeks.
Then it's back to me to work on the points raised by my editor - I do that and there's a bit of back and forth before it's ready to send to the copy editor. so we're talking maybe 4 weeks here as well.
The copy editor has the manuscript for 2-4 weeks and then it's back to me for any further adjustments about another week.
What does that all add up to well when I wrote Jack In A Box and was working 35 hours a week and commuting for 12 hours a week it took me some where between 57-76 weeks - yep that's over a year and up to a year and half. Now I estimate the process is down somewhere around 31-50 weeks, which is still a heck of a long time.
Now this is just my process and I'm sure if you were to ask other authors it would vary but one thing we'd all agree on is it takes time and this is why you see us get so excited when we show unboxing videos or get reviews, each book contains more than just our words - they contain a piece of our hearts as well.