When the work measures 22-23-24-24 (25-26-28) cm [8-5/8" - 9" - 9.5" - 9.5" (9-7/8" - 10.25" - 11")] bind off for armhole at each side every other row: 3 sts 0-0-0-0 (1-2-2) times, 2 sts 3 times, 1 st 1-1-1-3 (2-2-4) times = 60-66-74-76 (78-80-82) sts.

Updated sketch

Updated sketch