I'm thinking (but I ain't researching again) Rives Audio gives a general initial toe-in aiming point of five feet centered in back of the sweet-spot listening position. Seems like that's how I basically set mine up and didn't move them much from that position. It's been awhile though.
I betcha can read a thousand different ways of setting these speakers up from a thousand different and knowledgeable (expert?) sources and you'll find a thousand different answers.
Whenever it comes to main speaker placement, this stuff is so subjective and there has to be a million different room setups that I'd darn near throw out all of the thousand expert opinions and tune the system like I want to hear it, in MY environment. I typically use their advice as a starting point, nothing else ... most of the time.