I'm a business coach. I plan to write a book to market my business. How much of my book writing, editing, printing, etc costs are expenses for Sch C, line 8: Advertising?

In the year 2020, lots of us independent Sch C business people often hear that- "Your book is your new big business card. So you need to write a book."
How much of the cost to write, produce, edit, print, etc. my business book is a business expense under Sch C, line 8: Advertising expenses?

OR  Does the cost of producing my business book go somewhere else on my Sch C?
Please advise. Thanks!