Apologies to you Eagle. We had a newbie troll who got things going all over the place. That's why things got as heated as they did in the other thread. You might notice that all his posts are gone now. Thankfully.
Th others have said it well. Use you Polks until you can pick up the 4s or the 8s. I heartily recommend that you do so in the future. I cannot tell you how wonderful my QS8s are. I've had two different fellows come over recently to listen my Axioms. They were complimentary about them all, but they waxed poetic about the QS8s. They do a wonderful job.
Since you already have the sub, by all means go for the center first. Then you can replace the sub and surrounds when you are able.
Nice to have you here.