My thoughts on evac which I posted elsewhere today (edited minorly for content since posting guidelines there are more lax):

In Florida, our Emergency Management folks don't mess around. You will be given at least 72 hours of evacuation time. If you take either I-95 or I-75, you will encounter heavier than normal traffic flow, but there will be gas the whole way (or trucks on the way to refill). The line will move, but there's a secret. If you pay attention to the NHC (or this board), you'll have plenty of time to get the jump on folks. Just do your preparation now if you're in that cone. Have things packed for a week out-of-town and ready to load if/when needed.

OR...

Wait until about 6 hours before you receive TS force winds. You'll find either interstate to be almost completely devoid of traffic and will make better time than you ever have before.

Most importantly, know what you're going to do and where you're going to go NOW. If you're hoping to get a hotel closer than Virginia, you better make your reservations NOW and make sure to confirm.

So, in short (as a former inhabitant of Bradenton who remembers the flooding from the noname storm in the early 90s): go ahead and make your arrangements, but don't leave yet. If you know a friend on the east coast of FL, or someone further north and farther inland, you arrange to stay with them in a few days. Then you wait. The E/W roads (aside from the turnpike and I-4) tend not to be so crowded. If for example, you knew someone in Indian River or Brevard Counties, you take SR 60 (I think) across the state and it'll only take you a few hours.

The major highway flooding comes with the first mandatory evac notices. If you are prepared to, and leave within the first hour or two, you'll be just fine. If you wait just a little bit, you might find yourself in the logjam. That jam moves, but not very quickly at all.

If you feel you've missed the window and want to evac to the north, simply wait a bit longer and enjoy the slightly rainy/windy drive on an almost-empty interstate.

YMMV SPSFD