Absent bad weather/mechanical, you'll have plenty of time.
ATL-MCO is basically hourly or nearly. JFK has many more international connections and less flights to MCO.
Worst case ask to be routed
- on AA via MIA,
- or just route to MIA/FLL and use Brightline (train that isn't Amtrak)
- You could also fly into DAB/TPA instead of MCO if MCO is full. (TPA likely better due to location of Disney)
There's lots of options to get you to Disney fun the next day.