I keep an eye on what my local Indy/art house theaters have coming up, it doesn’t catch everything by a longshot but it usually does a pretty good job of catching some of the highlights.
I am lucky enough to have a good handful of those theaters reasonably close to me, and to some extent they seem to coordinate with each other so they’re not all showing the exact same movies.
Even if I don’t get a chance to see the movies in those theaters, it at least gives me an idea of what’s out or coming out soon.
Also support your indy theaters in general. The ones near me are generally a bit cheaper than other theaters, and while the seats may not have the latest reclining gimmick or whatever that the major chains are rolling out, the floors aren’t sticky, the audience stays off their phones, the staff actually gives a fuck, and often the buildings are just a lot more ornate and interesting than modern theaters. Just an all-around better experience.