Hi, Brandi! Nothing wrong with a last minute decision if it leads you to going to Disney World.
The first thing I'd recommend you do is try to
make some advance dining reservations. A lot of the more popular restaurants and dining times will already have been snatched up when people could make their reservations 180 days in advance, but you've got to try.
I'd recommend trying to get in at least one character meal and one nicer sit down meal. For character meals, see if anything is available for Ohana, 1900 Park Fare or Donald's Safari Breakfast for breakfast. You might have better luck with the nicer sit down meal. I'd recommend looking into Yak & Yeti, Turf Club, Biergarten, Mama Melrose's, Captain's Grill, and Kona Cafe. Since you'll be in town for more days than you have park tickets, think about dining at a Disney World resort (not in the parks) on those days.
Next thing to do is plan out your days. For this, TouringPlans.com will be indispensable. Follow the crowd calendar vehemently and pick a touring plan to maximize your efficiency.
Since your trip is right around the corner, you can get a good idea of what's going on in the parks when you arrive. The website wdwent.com currently has the entertainment listings for all the parks the day you arrive. The times for the following week will be suspiciously similar to the previous week.
After you've had a chance to digest all this,
drop me another question for help with specifics!