As it turns out, I don't have white in the 20/2 cotton. So I'll be using this taupe-colored yarn for my January towel. It certainly won't be reminiscent of snowflakes as in the original article. Oh, well.
The article says to weave the towels 38" long. It's not real clear whether that means 38" worth of warp or to allow for takeup, so I'm hedging and adding 10% for takeup. And I'll allow 24" of loom waste (this depends on your loom and your method of tying the warp onto the loom). I want to make 3 towels, so each warp end needs to be 1.1 x (3 x 38") + 24" = 149.4" or about 150", or 4 yards 6 inches.