You can get an idea of availability on the app. I like checking wait times and LL availability a week or two before a trip. I suggest checking on the same day(s) of the week you will be there. So if you will be at DL on a Saturday, entering at noon, check on that same day/time a few weeks in advance. Then you can see if there is typically decent availability. There are some rides that run out early in the day, like Indy and Space Mtn. If you can grab a LL for one of these as soon as you get there, even if it’s a late return time, you should still grab it and you might be able to modify it for an earlier time.