There are two reasons to prepare yourself first: 1.) You will feel more comfortable with the material, and 2.) With practice, you will begin wiring your brain for calmer responses to stressful situations.
Example:  Linda was an excellent elementary school teacher who I had the privilege of observing on several occasions.  In emotionally or behaviorally charged situations, when her students had trouble following directions or were rowdy, she did the opposite.  Quietly, without words, she would walk over to her desk where she kept a novel open, face down.  She’d sit down, put her feet up on the desk, and begin to read to herself.  Within moments, the kids would notice she had retreated, and like magic, they would fall in line.  Linda had practiced this response so much, that it became automatic when the situation called for it.  The children had also experienced it enough to feel its calming effect and responded to her energy, or co-regulated.
Whatever strategy you develop for chaotic situations, the more you practice it, the more tightly wired your neuro-connections become for that response.  It becomes a new habit!
Practice does not mean sitting meditation for long periods every day.  It does mean taking breaks “short times, many times.”  (Thich Nhat Hanh)  So use these simple lessons in breathing, using your body, and tuning into one or more of your senses for those breaks in the moments you can find during your day.