Before you begin, develop working deadlines with your creative team. Your designer/writer should help with this. Deadlines include initial copy/photographs submission to designer, return of 1st draft, review and revisions, final sign-off, and end product production.
This is a collaboration, but you are the dictator. Set some working deadlines; make sure you stick to yours, and make sure your team sticks to theirs.
There’s nothing worse than having a project just keep hanging on. Plus, you’re losing money because your new marketing materials aren’t circulating to your potential customers. And that’s not good.