“What I usually do is my slides first because I don’t have much time, then I start on what I want to say.” / “I don’t prepare because I don’t have much time.” He doesn’t have time to prepare what he wants to say because he does his slides first. She doesn’t have time to plan precisely because she doesn’t plan.
Approaching the preparation of a presentation this way you mix two steps which are better kept separate: structuring and preparing the content, design of visual aids.
Separate the first from the second: do a mind map, then your cue cards and finally your visuals.
This way you’ll use more oratory, less PowerPoint and the preparation process will be less tortuous.