This training is from the 40 Hour Teacher Workweek; I'm sharing this with permission. Since students only see you 1x each week, I recommend that you choose just 3-5 attention getters and use them over and over.
Minimize transitions - ideally they should come in and gather where they can see the projector while you give instructions, then transition to the computers for independent work or to participate in a whole class synchronous activity (such as a Kahoot or Jamboard). If this is the routine every week, it will happen very smoothly.
Teach classes to give you Jazz hands when you need their attention (and hands) off the computer.
Create a "ready to leave" diagram to visually show where the mouse, keyboard, and headphones belong when class ends. Make a plan for any student assisted sanitizing and do it the same way every time students are in the room.
Allow enough time at the end of class for students to clean up and line up, they should not be scrambling to get lined up when the teacher comes to collect them.
If your class is lined up and waiting for the teacher, facilitate a conversation with the students about what they are taking away from today's lesson.
What are you proud of? What challenged you today? What are you looking forward to next week? Tell me about something ah-mazing you saw a classmate do.