Among them, the most important factor is your writing speed. If you write quickly, it may only take a few days or weeks to finish this paper. But if you are a slow writer, it may take months or more to finish.
Besides, there are many other factors that will affect the time for you to finish your thesis, such as your workload, the complexity of the research topic, your writing level and familiarity.
Therefore, it is not a simple matter to accurately estimate how long it will take to write an 8000-word paper, and many factors need to be considered. I suggest you make a reasonable plan and work hard according to your actual situation.