Swatch Question

I’m kind of obsessed with the thought of 12 pair of socks in 12 months idea.  I’ve been stalking the sock pages in the pattern section of Ravelry. I’ve been fingering all my sock yarn.  I’ve gotten out almost every sock book I have.

This obsession brings me to my question. When it comes to swatching for socks, I have been experimenting with the gauge of a stockinette square vs a circular swatch. I find, for me at least, that the difference is so small as to be negligible.  I was wondering if that’s true for a lot of people, or am I just deluding myself into thinking it’s true…the measurements don’t lie, though, right?

Another sock knitting question.  When you are getting ready to knit a pair of socks do you choose the yarn first and let it lead you to the right pattern or vice versa? I tend to pick the yarn first, but am working on picking the pattern and then the yarn.  I’m curious about what others do.