This seems to be a brand new system they are testing that changes daily, so things might be different in October. We were there Wednesday (Aug 4) until today (Aug 8). We had mixed results, but most days were able to get a spot (or two). It obviously depends on how crowded the park is. Our first day wasn't as crowded. I asked a worker if they dropped at specific times - he said yes and listed off some times. A lady near me overheard and after he left, she said he was wrong - that they release throughout the day. (?) She and I stood there and both got a time (We weren't near one of the times he had listed). That day was great and it let me reschedule a little when I needed.
The next few days it was more challenging. The ride goes down fairly often. That delays the times and then they have to move everyone. The app constantly changes the ride time without notifying you even if the ride doesn't go down. It would move me forward in time or backwards in time. Usually small amounts, but sometimes over an hour. If my phone is in a locker in the other park because I'm in line for a ride like RRR and it jumps me forward by an hour - that can cause a problem! It says it will let you push the time back. After that first day, it never let me. Either it just wouldn't adjust it, or it would and then a minute later bump it back forward. That was incredibly frustrating.
I had the best luck getting a spot right around 9:00 am. I was successful most days at other times, but some days it was just too complicated with dinner reservations etc. I like the system in theory, but in reality, there are some flaws. You do have to reset the app each day. Also, not sure you can reliably check if you are not on property while checking - you have to allow location services and you must be on site, so your tests might not be accurate. But I would just constantly refresh throughout the day and it would randomly pop up. If it goes down for a long time, your chances will be smaller.
That said - the ride was amazing! We loved it and got to ride multiple times!