OMG...DRIVE!
If you fly, you will have to drive to the airport -- arriving 1 1/2 - 2 hours prior to flight time if you are checking luggage. (Staying for 8 days, you probably are checking luggage). So, right there you have 3 hours.
The flight should be about an hour -- 1 1/2 hours with taxi time on both ends. Another 2 hours.
You will need a rental car (another 1 hour), or you'll need to pick up your luggage and get to DME (30 minutes minimum).
So -- to get on your way to WDW, you have already spent 5 1/2 - 6 1/2 hours. And you're not there yet!
Just FYI, WDW is a 30+ minute drive from Orlando International Airport, and DME could take 1 1/2 hours...or more.
According to Google Maps, driving Pensacola to WDW is 6 1/2 hours and it's all expressway. I-10 East to I-75 South to the Florida Turnpike to a short stretch on I-4.
And -- if that's not enough -- if you drive, you have your own car available for offsite dining and shopping, which are better and less expensive.