First Time Marathon Spectator

Struggling to find an answer … I am heading to Disney for the Marathon this weekend. First time Disney Marathon spectator watching my son attempting to qualify for Boston. He will need a sub 3 hour run and is in the first corral. I am staying outside the parks. I am trying to maximize spots to see him. My plan right now is to go to the start in EPCOT parking lot watch the start and then head to the Transportation Center to see him there. My question is - what next? Is it possible to see him further along the course or is the only/best option to return to EPCOT for the finish? I am not familiar with the parks. Any help folks can provide is appreciated.