I don't do the I-75 route to FL very often, only to outrun a storm or if heading to the panhandle, but do the N -S run a LOT.
As general comments, the biggest one is weather. Be flexible by a few days, watch the coming weather, and where it's coming from. Try to leave 24 hr. after a storm, dry roads and unlikely another will be on it's heels.
We always try to get as far south the first day as possible. Mind you in a M/H it's easier because everything is per warmed from the drive. I just find the odds are better if you're further south that bad weather will mean rain not ice & snow.