Ideas are something I never struggle with. I am always at different stages with writing a book. I currently have 4 ideas for novels that will come to fruition, but some of these may be years away. I will collect ideas for these books and jot them down, they may not mean much at the time but I know they will become important later.
So to the process of writing a novel. I will collect the ideas, as above until I consider there is enough to put something together. Next I outline these into ideas and notes for chapters, each of these may take a few days to collate, with new takes on the original ideas. When I am satisfied there is enough material, that outline is completed and I move to the next chapter with the same process. Eventually after a couple of months of that process I will be ready to start writing.
I write everyday but not too much, I would usually aim to complete a chapter of 4,000 words every week. I don’t worry if I miss days or don’t complete I have no set routine. Again I will write in different places or actually write at the scene I intend to create. In-between I will confer with friends and adapt or change little processes. Long cups of coffee come to mind lol. I would expect that process to last 6 months.
I would then spend lots of time re-working the chapters, getting friends to read and going over grammar. Then and only then is it ready for the editor. I would expect to work with an editor for a month depending on how the process goes and how well they think the book has gone. Then off to the proof reader for a couple of weeks.
Lastly is all the re-reading and checking again, your last chance to change story lines and believe me it will still happen, and you will still find mistakes!
I never worry about time, much to the frustration of people around me. It might be 18 months before the book is ready to put out. I always like to take things slowly and let nature take me to those right places. I never force the issue or say it has to be done. I especially take my time when writing any prose as this is something close to my heart and needs to be just so.
My advice and it is only my opinion… never rush, think about what you want to say, listen to peoples criticisms and take away positives. Know inside out what you are writing about.