Files just uploaded appear on top of the timeline, for the moment, and then when you refresh or change the view they take their places by descending chronological order.
Pictures with no metadata datetime will be updated with one during the upload. The time added is the time of the upload of course.
GoOz
commented
7 years ago 
Files just uploaded appear on top of the timeline, for the moment, and then when you refresh or change the view they take their places by descending chronological order.
Pictures with no metadata datetime will be updated with one during the upload. The time added is the time of the upload of course.