Are you Gold or Platinum Medallion? If so, changing your flight (within 3 hours of the new departure time) is free on the day of the flight.

For example, if you're on a 2pm flight originally and you want to change to the Noon flight (2 hours earlier), you can call Delta at 9am (3 hours prior to the new flight) and you can get switched for free as long as there is a seat. If you are Silver Medallion, you can also do this, but it costs $50.

I am not sure about non-medallion fliers. Anyone else out there?? Is it also $50 for non-medallions, more? Or are they not allowed?

This works if you want to wait until the day of the flight. If you want to call ahead of time, you can ask politely because of the short connection time. Since you're connecting to international and only have 45 mins, Delta should help you out. Good luck!!