Due to the large number of points I had to first circumvent the 1000 point limit un arcgis.com - it's mostly to maintain browser and server performance - it's quite easy to change when you publish the service from ArcMap. I was warned however by Esri support that I might reach performance issues regardless, and mega-datasets are really meant to be on ArcGIS Server not on ArcGIS Online. Sure enough even if I filter the data to a single nationality, the time slider cycles through time frames faster that the browser can refresh them from ArcGIS Online.
|clkck image to enlarge or go direct to webmap|
So until I giscloud.com or Mapcentia mentioned last month add time-stamping capabilty on their postGIS backends, we're left with either loading data on servers ourselves, or posting data in time-slices, or posting layer packages as I've done earlier. QGIS also has time-stamping added now programmatically according to Anita Graser @underdarkGIS, tho I'm not sure how that translates server-side per Jo Cook's @archaeogeek caveat.
So better let the heavy pulling to some, while the light speeds gallop on...
(heavy-horse pulling and chuck-wagon racing from 2014 Calgary Stampede)