Great advice. I used to follow it when my five children were little. They range in age from 19 to 26 now. So this advice is obsolete for me, right? Wrong!
My babies now are the creative writing class I am teaching. We go over all kinds of preparatory lessons in class about description, dialogue, the hero's journey, etc. We write snippets, we free write, we share, we discuss. And we write. In class. The students eagerly grab the assignment, move to a comfortable place on a chair or the couch in my classroom and write!
So when they write, I ... clean my desk, plan lessons, put grades in the computer grade book, schedule meetings, block scenes for the current theater production, etc. etc. etc.
Why don't I write? It is the age-old issue: There are a million things to do and writing seems a guilty pleasure.
But today! Today they are starting their first short story. They are settled and creating. Quiet. (which is unusual in my creative class room) I scan the room and they are earnestly working.
To my left is a contract for the musical along with information for the playbill and posters. To my right are entry forms for a music festival. Across the desk are pamphlets for the concert tour of Ireland. So much to do.
But today, while my writers are writing, (while my babies are sleeping), I join them. I write.