I'd say a little further from the back wall (3 feet), and a bit closer together (6ft) ... how far from the plane of the speakers do you sit ? I've found an equilateral triangle works well. Toe in helps mostly if there are side walls present, but a slight toe-in could still help you.
There's no precise formula so little movements might make big differences.
There's no precise formula so little movements might make big differences.