The pattern says 2 24inch size 3 circulars but how does the cable length matter that much?
When knitting socks on circs, I’ve found the 24" to be perfect. I was using 16" and 24", but when u increase the length for 16" to 24" the actual needle gets longer, making it easier to handle for me. But, if u have 2 circs in the size needed already, I say give it a go 
Oh, I forgot to mention, the longer cables have a bit of a tendency to get tangled together 
I think part of it is what you are comfortable with. I am doing a pair with 16" and 20" needles since I already had them. I have found these to be a bit shorter than I would prefer. Also, having them different lengths has been a bit troublesome as well, but nothing major (mostly making sure I don’t pull the sock off of the shorter cable while working with the longer one).
Thanks guys are you using size 3
depends on the yarn and the tightness of your knitting…if you’re using fingering weight sock yarn, size 3’s might make the fabric a bit loose.
Do you think size 2 32 inch circular needles would be ok?