A room must not have long decay times. I prefer broadband absorption on center portion of back wall, front wall, and ceiling to achieve such a room. Other than overall room decay times, the area behind your front radiating speakers, especially closer to the corners, would be acoustically relevant for bass absorption.
I notice you have some very, very nice loudspeakers.
This brings us to your early reflection points. There are serious minds (Floyd Toole, Linkwitz, Manny LaCarrubba, Professor David Moulton) who are of the opinion that lateral walls should be reflective when using good speakers. Such a wide dispersion speaker can generate side reflections that are tonally similar to the on-axis response. This is said to generate very stable imaging, improved intelligibility of speech and music harmonics, and imparts a larger size to the soundstage among other things.
This thinking is deeply unpopular amongst many professional acousticians, and more so among stereo and HT enthusiasts. I personally think the Toole/Moulton camp are on to something. But you can A/B for yourself. Just keep within a few rules (reflections within 6 to 30 milliseconds, room should have controlled decay times...)
Tumara Baap