You don’t want to leave preparing your slides until the last minute. Not only is this unprofessional, but it sets you up for failure, as you will not have any opportunity to practice the talk to learn which elements work well and what your timings are like. If you plan and design your talk and slides as early as possible, then you have plenty of time to rehearse the talk and make necessary changes.
Getting Started
When your slides are ready, you should first run through the talk by sitting at your computer. ...