I plan to hold my own classes. Would I give each and every participant paperwork to fill out at the time of the class?

This will be my first time holding my own group classes. I’m covered with the insurance I need. I just need to know about paperwork (eg. Contract Forms, Par-Q Forms etc). How would I have them go about doing the paperwork? Would I have them fill them out on site at the time of the class or a day ahead? What would you recommend?