Recurring app starts should bring the user back to where he left. The user should have context what he looked at when last using the app. That counts for the scroll position in the timeline and selected events.
Load a maximum of 100 events. Show the loading spinner until the events are loaded and display them all at once. Don’t show multiple spinners, just one! This happens only when the timeline is empty like the first time opening the app.
Drag down on timeline to update manually. Always fill the gap between last timestamp/event shown and most recent. Load a maximum of 100 events, if there are more events show a button “More Reports”.