It's not critical. The size of the stitch really is dependent on the needle you use to knit off the cable needle with. You don't want it too large, though, or you might stretch out the stitch you're picking up with the cable needle.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry