it depends on:
How many stitches,
how many ribs
and where the beginning of round is..
and possibly, how the socks are being knit (on 4 DPN's? on 5 DPN's (on 2 circs or on a single magic loop)
In many socks, the beginning of the round is CENTER BACK
but for me, because i knit my socks 2 on 2, my beginning of the round is at the side --both socks same side
sock 1>>(BoR) sock 2>>(BoR)
some directions have side (seam) BoR, but like this
<< BOR sock 1, and Sock 2>> beginning of round..
And some socks have Ribs so that the side 'seam' is a single k (k1) then the pattern is P2, K2, P2 (and the front ends with K1, making the side 'seam' fall in the middle of Knit rib..
this Results in a K2 column dead center..
but other socks start with K2, (p2, K2,....and end the front with P2 (and start back with K2.. (and end at the side 'seam' with P2.
With version 1 (k1, then P2, K2, P2.. K1) the center front will be a CENTERED RIB (likely a K2)
but with Version 2 (k2, p2....) the center front will be the imaginary line between 2 knits and 2 purls..
(and if you want to have things centered..?) then you need to think about how the cable is positioned on this imaginary line!)
Some knitters are anal about these details..
and some knitters aren't.
some knitters move stitches around 1 or 2 stitches --on the needles or just by moving the BoR marker.
It really is a fine detail..
are you going to notice if you center front is 1 or 2 stitches 'off?) (are you going to care?)
if yes, figure out what you need to do to center cable..
if not, just make 2 identical pairs..
(me, i don't care much about these fine sock details.. but cast ons? that's where i get anal and persnickity!--pick your battles.
Its perfectly OK to be persnickity about making sure your center front of a sock is centered on a K2 rib, (and not between K2|P2-) but i am not!