I have to say that my initial reaction is that if it were me, I don't think I'd plan on a park day that first day. Here's why - figure that it will take you at about 2 hours once you land at MCO to deplane, get your bags, check in at Magical Express, board a bus and get to the Poly. MCO is a good drive from WDW, so if your plane arrives on time, it's still going to be about 1 pm before you get to the hotel. Check in at the Poly is relatively efficient, but it does take a few minutes, even if you are first in line. I believe that you can have the luggage taken to the room while you go do something else, like go to AK. It takes about 20 mintues on the bus to get to AK from the Poly, but you might have to wait a few minutes for a bus. So, it's probably about 1:40 or so that you are arriving at the entrance to AK. Now, admittedly, getting to AKL for a Boma reservation is probably easiest from AK, you still would have to plan on leaving AK to walk out to the bus to AKL at no later than 4:15 (and to be honest, I'd personally leave no later than 4 for a 4:45 reservation). It takes a few minutes to walk from the entrance to the buses, to wait for the bus and to get to AKL, and to walk up from the bus stop at AKL to Boma. That's not much time in the park and to me a waste of a ticket day. Given that your DW is expecting and it's going to be hot, her ability to hussle is probably not going to be as great as if it were cooler and she were not expecting and having been up since 4 am, the entire party's energy level might be somewhat lacking. If it were me, I'd probably suggest to my family that the time between checking in and leaving for dinner would be best used to relax at the Poly, have a light snack, and get settled in for the rest of the vacation. We (DH, DD5 and I) are going in December and staying at CRS. We're driving up from Ft. Myers and don't expect to get to WDW until mid afternoon. We are meeting up with nephew and his family for dinner at WL around 6, so we are not planning on going to any parks that first day ourselves.