This happens often, especially with 30-day booking. The best thing to do is to start hacking the night before you go to the park. You’d be surprised at how much opens up! If no luck, of course continue to try the day of. If the ride has a Day of Drop, definitely try those, although they’re not a guarantee.
If it’s something that is a must-do for your family, consider rope dropping or using the end of the night strategy based on what works for your schedule. Here’s a good post on the blog, and the strategies here work for many rides, not just Flight of Passage as described.