Beginner here...i finally found a skull cap that my husband likes and I am getting ready to knit it for him, but the pattern only says to use 10 US size circular needles - not the length . The cap is 23" in circumference - what length circular needles should I use? I'm thinking 16"?? I know that I will need to switch to dpns as I decrease (no prob since I just finished my first sweater [yea!] and used them for the sleeves). Any suggestions? thanks guys!