Duke has it right. I assume neither speaker is in a corner? If neither speaker is in a corner then you have six early reflections to worry about, two between the speakers, two on the ceiling and two on the floor. The two between the speaker are the ones to worry about first. Moving the speakers just shifts the early reflections a little and delays their timing a little. If you treat them correctly moving the speaker does not matter! You can actually put them closer to the wall. The mirror method Duke describes is the way to find them. Sit in the listening position and have a helper hold a mirror against the front wall at ear level and have them slowly move it until you can see the speaker in the mirror. Mark that point. Then do it for the other side. Get 4" acoustic tile from here
https://www.foambymail.com/acoustical-wedge-foam.html They are dirt cheap and allow you to experiment. If you want something more fancy looking you can get that later once you know what you are doing. Place 4 tiles at ear height centered on the early reflection points arranged in a big square 2 X 2 feet. Then have a listen. You can do the ceiling if you like. On the floor use a rug or carpet. Try making the squares bigger 3 X 3 feet and see what it sounds like. You will change the frequency response of what you are hearing a bit dropping the high frequency content. A pro will measure it with a microphone and if needed make corrections by digital EQ. Unlike analog EQ, digital EQ will not add distortion or phase issues. Other than the frequency response changes it is invisible.
Personally, I do not think you can overdo it. Adding more absorption does seem to make the system seem more dull but in my experience if you want the sensation of having instruments hanging in space, like you can reach out and touch them you need to severely limit reflections. Those of us in the know use speakers with very limited dispersion and kill the early reflections as much as possible. People will initially think these systems sound lifeless until they sit and listen to them a bit and realize that no frequencies are missing and the image is spectacular. The room has disappeared. For the best performance IMHO the location of the listening position is more important than the position of the speakers. It should be no further away from the speakers than the 1/2 way point in the room. This breaks up the timing of the various reflections best. As for bass just move the listening position forwards or backward just a foot or two until you like the bass you hear or add digital room control. The Trinnov Optimizer is the best currently available, the DEQX unit is the best value but has a very steep learning curve. Audiophiles tend to shun these units until they compare active to bypass. Every last audiophile that has heard this in my system has gone out and bought one. The improvement in imaging and overall realism is that obvious.
If you want to know if your speakers can image beyond themselves get Roger Water's Amused to Death. If I remember correctly the radio should seem as if it is coming from the left side wall and the dog barking should come from the right side wall.