A small, uniform delay between the start times of identical animations across a group, so elements arrive in sequence rather than as one block.
Stagger the list items by 30 milliseconds: the panel should feel assembled, not dumped.
Stagger is choreography: it tells the eye what order things matter in. Keep the offset barely perceptible (20 to 40 ms) and hold the total duration fixed, shrinking the per-item delay as the list grows, or a long list becomes a slideshow. The masters stagger exits too: the interface should leave the room as gracefully as it entered.