The more detailed itinerary was available the night before. Factba.se published the Presidential Calendar, with the specific times and general locations (including the airport) on the President’s schedule. Of course, the timeline can change based on delays in the schedule. Today, Factba.se initially published the wrong times, which conflicted with local news reporting. I was able to determine who was reporting the correct timing by consulting the White House Pool ReportsTwitter feed.
If you want to photograph Air Force One, some online resources can assist with the planning. First, the Defense Internet NOTAM Service provides an early schedule for the President’s arrival and departure. Read the Presidential TFRs for temporary flight restrictions for VIP movement. The FAA published the applicable TFR three days before the President arrived.