specify a time for zoom call

Hello. When you open the Zoom desktop app, you can change the start time to whatever time you want. For example, I have a meeting in the attached screenshot starting at 7:07 am. You can change the time by typing in the time, or you can use the up and down arrow keys on the keyboard to go hour by hour or minute by minute. 

I hope that helps and please make sure to mark the solution as accepted if this information is what you need.