As a former cruise sales agent, I would caution about booking a flight out too early. I assume you are cruising out of Port Canaveral and flying out of Orlando?
There are a lot of potential delays in that scenario. Ship docking late, not getting off quickly enough, delays in your transfer/traffic to the airport, long lines for security, etc. I personally would not book a flight for a customer that fell before the cruise's recommended window, for those reasons.
Now, can it be done? If everything lines up correctly, absolutely. But ultimately you have to decide if the risk is worth it. The airline will not give you a refund or put you on the next flight if you don't make it in time, and you'll be stuck at the airport booking a very expensive last minute flight, if anything is even available.