Day of Coordinator duties: 
Full Day Coordinator
2nd coordinator available if needed
Execution of your timeline
Keeping everything on schedule
Main point of contact for vendors, guests, and venue personnel
Make vendor payments as needed
Ensure that the ceremony and reception spaces are decorated correctly
Coordinate DJ music for ceremony processional and recessional, grand entrance, and dances.
Work directly with DJ to make all necessary announcements
Line up wedding party and direct them on processional
Keep venue staff/caterers on task to keep plates picked up, trash cleared, etc.
Any other duties that you will need to make your day as stress free as possible can be discussed.