Wanted a picot edge just before the change to green yarn. With this yarn, used a size 7 needle and 84 stitches to get the right size.

Used Picot Cast On Tutorial , with a twist to start:

Cast on 6 stitches.
Knit 2 stitches.
Bind off one stitch on your right hand needle, by slipping the far right stitch over the second stitch that was knitted.
You have one stitch left on your right hand needle.
Knit one stitch.
Bind off one stitch just as before.

You have 3 stitches left on the left hand needle, and one stitch on the right hand needle.

Slip the right hand needle stitch (remaining), onto the left needle.

You now have four stitches on the left hand needle.

Cast on six stitches with knit cast on. Repeat with knit 2, bind off 1; knit 1; bind off 1; slip RH stitch to left needle.

Continue until there are 84 stitches (21 picot). PM. Join and continue knitting in round until piece measures 1.5 to 1.75 inches from picot edge. Bind off. With crochet hook, slip stitch white yarn on the wrong side to the picot edge. Pick up 84 stitches with white yarn. Change to green yarn and follow pattern to end.