I've never driven it, but looking at maps.google.com directions, it's 11-12 hours from Buffalo to Charlotte, NC. That is taking I-90 down to Erie and then down I-79 then to I-77. Google says Orlando is 20+ hours straight through...
It looks like another hour and you would be to Columbia and yet another and you could be around I-95.
so if you leave at 10PM look to be around Charlotte, NC by 10AM (providing you drive straight through)
sorry I can't speak from experience...
Good luck, and I hope you have safe travel!
Later,
Paul