Curious, why do you want a 3 second delay?
From the screenshots, I can see that the list is generated via a backend workflow which means you cannot quite estimate how long it would take yes? If your goal is mostly UX driven, then I’d suggest creating a custom event. Something along the lines of:
When button is clicked > [step 1] Add a pause before next actions (3 seconds) > [Step 2] Show Repeating Group
Perhaps if I know why you require the delay, I can profer an alternate solution.