Using more than presentation in meeting.

I would like to use an informational slide presentation before our program. I am not sure about about the equipment I might need.

This is my agenda:

In opening Zoom portal I plan to show information (Announcements) slides as guests enter. Do I begin share screen before or as I allow participants entrance?

Following the opening slides, I begin my program with introducing speaker. Now I must prepare the presentation for viewing.  

My question is how do I make the transition from opening slides to speaker presentation. Do I need two computers operating? I have the presentations on a usb. Thanks for your time. and expertise.