Casting on in middle of project

I am knitting a baby sweater. The pattern tells me to slip arm stitches onto stitch holder, then CO one 1 tightly. Next knit the back of sweater stitches, slip arm stitches onto stitch holder. Then CO stitch tightly, placing a stitch marker to mark new BOR either after the CO stitch (if only one) or between two of the cast on stitches. These stitches will be the underarm. Then I am to start to knit all stitches for the body. Does this include the new CO stitches. Is this going to make sense when I just do it and start knitting. The body stitch count says I should have 88 stitches. This information is after the CO directions. But if I make the CO stitches I will have 90 stitches. Should I still make them and decrease somewhere else? Do these stitches hang differently for the underarm? Does this even make sense?

Thanks!

Yes, it’ll make so much sense when you’re at this point in your knitting. Cast on the new sts and continue knitting around and the new sts will get knit on the next round. If it says you have 88 sts after you cast on the sts, that’s what you’ll have then, before that maybe you had 86 so if the number is given after you cast on, that includes the new stitches. Everything will come together as you get there and follow the instructions. Don’t overthink things.

Thanks! Got it!