I'm doing a bit less shaping for the waist.
After the ribbing, I will knit to a total of 4 or 5 inches and then begin to decrease
My dec round : K4, k2tog, k to 2 st before m, ssk, sm, k to next m, sm, k2tog, k to 6 st before m, ssk, k4 then repeat all once more. Knit 5 rounds.
I’ll do that 3 more times, see where I am in relation to my waist.
To increase : K4, M1L, k to m, M1R, sm, k to m, sm, M1L, k to 4 before m, M1R then repeat all once more. Knit 9 rounds.
K to m M1R, sm, k to m, sm, M1L, k to m. sm then repeat all once more. Knit 9 rounds.
Repeat both sets of increases again.
If you desire a more straight/boxy shape, you could decrease at each side of the side marker, OR on either side of the waist marker twice. I'de probably do it a few inches from the rib, then 9 rounds later.
At the hem the stitch count is 8 stitches more than at the underarm.