Cast on 33 (37, 41) stitches and knit 4 rows. On the next row k4, M (place marker), k1,p1, M, p4 (5 6), M, p13 (15, 17), M, p4 (5, 6), M, p1, k1, M, k4.
Work up to the garter band. K2 tog, YO needles twice, k2 tog, k1. On the next row knit into the front and back of the YO. Repeat buttonhole every 2.5” twice. (Note: This makes a large buttonhole. If you want a smaller buttonhole k1, YO, k2 tog, k1)
Continue in pattern and working all the other increases until you have 37 (41, 45) stitches across the back and 22 (24, 26) stitches on each front and have completed a wrong side row.