We rarely hit the parks on our first day...even with a 7am flight (tough now with kids), we don't hit MCO until 10am. After getting a car and checking in, it's time for lunch.
Then it's off to a grocery store for supplies - BEvERages (although I'm not a big fan of American brew), soda and pop-tarts for breakfasts (love that sugar rush), snacks for carrying in the parks (goldfish crackers, etc), and the like.
Then, depending on who we are traveling with, we often split up. Some people nap - especially those who need a rest after waking up at 3am. Others, like me, go resort-hopping. I usually do a monorail loop, stopping off and remembering past stays at each hotel. Then I hop on the buses and just ride around, stopping at resorts that I haven't been to before. Then it's back to my resort - often Fort Wilderness.
The group, often my family, my parents and my sister's family, grabs dinner and then we vary up the evening activity. Poker or Euchure are not uncommon, with the Resort channels on in the background. My dad and I often hop in the golf cart for small cigar (kind of a ritual) and a drive to Crockett's for a nightcap.
Everyone who needs sleep crashes early. I never sleep more than 4 hours a night, so I have to force myself to sleep that night.