Check-in at counter up to 3 hours in advance all the way to 30 minutes prior. Call their res number for loads; reps have always been accomodating to me and spent the necesssary time to sort through different scenarios. I have been on them several times, always ZED fare, as I'm with my spouse and we don't even try if there's not some seats available. And the ZEDs are stupid inexpensive; plus no restriction on unlimited cocktails with ZED. I've found night before loads tend to hold true. JSX has always been a great experience for us. Nothing like boarding essentially at departure time, door retracts behind you, engine spins and you're gone. You'll feel like "somebody" when you walk off the jet to find a tuxedo-wearing rep with a "welcome Mr. & Mrs. Smith" sign at the open door of your rental car (Go Rentals is a JSX partner entity, sometimes the best price in the market, others not a great bargain. But the convenience is unbeatable, especially at airports that have no other rental ops). Since every seat is 1st class, it's the most assured upggrade and best value in the non-rev world. I usually shoot the breeze with the pilots and they always ask why I'm not jumpseating (see above reasons). They would be glad to have you.