Develop Your Storyline First
Important to structure the presentation before production begins. Also helpful to establishing the visible structuring devices you will use and sectioning the pieces off for simultaneous production by members of the team.
By defining your message first, you tend to create fewer charts and spend less time on the process. Without a clear notion of what you want to say, you tend to do a brain dump into the presentation, which has to be sorted and sifted though to eliminate the unusable stuff.
The anticipated audience and the timeframe will help determine what ;you need to/can say, so you won't develop charts in higher degrees of complexity and detail than you actually have time to use.