Many people say that you should find the time of day that you are most creative.
This is terrible advice. For a start, most of us have other jobs and responsibilities which take a large portion of our time. We only have a few hours in our busy day to get any writing done. So you need to sit down and write.
Amateurs sit and wait for inspiration, the rest of us just get up and go to work. (Stephen King)
Turn writing into a habit. Force yourself to sit down and knock out some quality work. Don’t feel that you have to get a certain number of pages done, just make sure you have done the best you can in the available time. It might a 10 pages, it might be 10 lines, get something on paper so that you feel you have achieved something.