Alright, this is pretty fascinating. This shows the ingest for tweets mentioning Mattis. It shows "Max Tweet ID for group, time in UTC, the number of tweets collected in that call (100), request counter and epoch time of ingestion.
Trump made his Tweet about Mattis at 5:21 PM...
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So the time Trump made his tweet was UTC 22:21 -- you can clearly see how fast news spread over Twitter once Trump made his tweet based on the grouping of time stamps. At the bottom, 100 tweets represented a gap of around 10 minutes ... then at the top it's a gap of 7 seconds.