These characters are picking on you. Spk. wire length is of no importance, but I would make it good quality 2 conductor #12 stranded. Low oxy. content is easy to get these days and relatively cheap. You will not hear it but it looks nice after a few years.
Time delay on the left/right channels relative to the center is the only concern for reasonable image stability. Place the spks. on the same horizonal plane. Then recall that the delay is about 1 ms per foot, and this is how you would move the left and right spk acoustically to achieve an arc in front of you with the center channel at the max distance (on the top view of the semi-circle). The left and right spks. should be on this arc. Fine adjustment would be handy (.1 ms) but lateral reflections (or lack there of) will swamp the detail. It depends on your room size and spk placement relative to the floor and ceiling.