Writing is not for occasional activity.
If you wrote a book, it doesn’t mean that your job is completed or you succeed or your writing will not come to an end.
Every writer has to write. If his/her book succeeds or fails. You must every day. You should write something good every day. You, yourself knows what is important to write. Whenever you feel, you can write. just start writing. There is nothing called good or bad writings.
I often say to myself. There is nothing called good or bad results unless you try. You have to believe yourself and start it. I personally do not know about entertainment writers. If you are decided, writing is my profession. You must start today. You must keep on writing, till your last breath.
People can say to you about the topics to write. But at some point, of time you have to realize,
what am I writing?
So far, the impact of my words to the readers.
My mistakes, mistakes, mistakes.
Where is the learning curve in my writing?
How can I give my best?
How could I able to cover the topics widely?
Am I specialized on a particular topic?
There is no prescribed time or word count to start writing. If you wanna be a writer, you have to set aside time for every day. The one more way is, set a target. Every day my target is 300-word count. Or you can have a special target.