You have to experiment. Too many variables to give an exact answer. Unless you have a speaker like Vandersteen, where they give you a set up formula. Then you would just use that, at least to start off with.
Speaker positioning toe and tilt
How does tilting a speaker effect the soundstage and bass response? Also, how does toeing a speaker in directly towards me effect bass as a result of a rear firing port now reflecting closer to the back corner of the room?