If you’re planning a new website, newsletter, blog post or other marketing piece, plan on copywriting being a painful process. I know this from experience both from writing endless copy for Promethius (such as this very newsletter article) and from working with countless clients on their own projects.
Copy is almost never delivered when promised no matter how fervently a commitment is made. The exceptions to this rule are professional content creators. Folks whose sole responsibility is writing copy for a living seem to have no problem with deadlines. They’re used to it I guess.