We usually get to our resort around 2 O'clock. After we check in we ride the MONORAIL to the TTC, then head straight for EPCOT cuz it's open the latest during the slow season when we go.
Same with me. We always head straight for MGM without question and head to ToT first, RnRc second. Then we just stay at MGM the whole day. The second day is always MK first thing in the morning.
For me it depends on the weather. If it's a normal sunny day I'll usually head to MK first just because I'm so in love with the scenery and it gets me in gear for the rest of the trip. However, if it's raining I'll go to Epcot since everything's in pavilions. Innoventions for me has always been a great place to ride out one of those massive Central FL thunderstorms.
However, no matter where I go first I always go to the TTC and take a grand circle tour of the monorail to take some aerial photos before heading for a park.