The number of days it takes to make a voyage such as you propose is the distance in miles divided by the speed of the
boat in MPH, divided by the number of hours run per day.
That's under optimal conditions. You should allow for
weather delays, no-wake zones and as others have mentioned, bridge delays. There will be many bridges along that
route and as you get closer to Miami, you will have to wait for some of these to open. Many are on a restricted schedule and open once or twice per hour.
So, figure it out and then add several hours for an estimate.