Once you create your presentation in Google Slides, you will need to PUBLISH IT TO THE WEB and set the auto advance timer to 20 seconds.
- On the home page of your slide show, click "file"
- on the drop down menu, click "publish to the web"
- On the pop up, click "start slideshow as soon as the player loads" (don't worry about the timer yet....)
- copy and paste the shareable link into another place (i put it in my blog as an unedited post)
- The last part of the link should be a number (the default is 3000, meaning 3 seconds). Change that to "20000", meaning 20 seconds
Link to my PK Presentation