Changing the background of selected item in a Repeating Group

After following the examples in the link below I found that I needed to have the first item in the RG selected, and therefore also with the new state selected, when I opened the page for the first time.

Has anyone found ways to set the first item in the RG to the selected state?

Custom state of a specific button inside a repeating group - Need help - Bubble Forum

Understanding Conditionals now…