When are the different cinema formats (IMAX, Dolby) usually announced?

I’m in the Northern Virginia / DC area and looking at advance tickets for movies coming out around the third / last week of October. I’ve noticed that some movies are available in IMAX, but not yet in Dolby. I checked the Dolby Cinema release schedule to make sure those films are being released in that format.

I’m a relatively new moviegoer, and I was wondering if anyone knows when theaters usually update / release Dolby Cinema showtimes.