You continue to work on the set of needles you're using. You'll work across the first 17 stitches. Drop that strand and start binding off the middle stitches with a new strand. You can just start knitting with it since the binding off will really secure it. Any end can be woven in later.
Now you'll have the two separate shoulders on your needles with a gap between them. Each will have it's own strand. You'll work one, then the other, on each row. The neck decreases will occur on the inside edge of each section.
Once they're on the needles, it will become clear how to do them.
"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