Making toe-up because I don’t have much yarn. so following Kittys.
CO 12, knit 1 round, inc 4 st on rounds 2 + 3, repeat these 3 rows until 322 = 64
Start heels:
Knit in stockinette stitch (knit all stitches) until foot measures 2” shorter than desired measurement from tip of toe to end of heel.
6,5 inches for me
Trusty

These heels!
https://www.youtube.com/watch?v=fDw7RSmxVxs&t=500s

And fold-over picot edge :
K2tog, yo; rep from to last stitch, k1.