Before you start an event, you need the necessary tools. One of these tools is planning.
In my years of being an events management professional, the common tools for planning are Gantt Chart, Daily Run Sheet (DRS), and Checklist.
This is what Jim Rohn is talking about when he mentioned about finished it on paper. Our mind cannot remember all the processes and things that we have to accomplish but if we have the tools I mentioned above, we will not miss a thing and accomplish most of the details you planned.