Also depends on the time of year you're flying. Weather can severely impact flights..on both ends. I tend to book any ADRs, on arrival day, at least 3 hrs after I hope to arrive at my resort. So, for a flight that lands at 5:20, I would assume you would arrive at BC around 7ish. Unless your flight is delayed for some reason. If it were me, I wouldn't book an ADR for your arrival night. Most places at the S/D allow for walkups, so you could try that. Worst case scenario, you eat at Picabu that night. You probably wouldn't even get over to the Dolphin until close to 8, if you arrive at BC by 7...by the time you get to your room, freshen up, then walk over to the Dolphin.