I agree with the "center first" recommendations. I should also add that the QS8s are the unsung heroes in my setup. They additional (ambient) audio they produce is still surprising to me. I had some old Boston Acoustics I replaced with the Qs and the difference is stark. Your plan will work and you should look forward to the delayed purchase of the Qs.
Why am I telling you all of this? Have you considered getting the center and/or surrounds from the factory store? Could save you some $$ and hasten your purchase to grat audio.
