The fact the shooter knew he'd be on the side walk at that time has to be one of the biggest clues. Who knew his schedule and routines?
Schedule isn’t a big clue since who knew: The whole world, it was their investor day. Their Investor Relations literally pumps out when these people are speaking, what location, what room, and the conference host will have dinner itineraries sent out weeks in advance offering seats at the table and the host company sales people will actively/aggressively look to fill.
6:45am EST is a pretty normal time for people to be up and moving especially on a packed trip or any C levels in NYC. Lots of breakfast meetings.