Pattern Help

[mare-nitt]

I need to know if I do this whole sentence 3 times, or do I just do the the 2 BO rows and then the dec row 3 times:
Working with 52 sts.
Armhole shaping: Working back and forth in rib, bind off 2 sts at beg of next 2 rows, then dec 1 st each end every other row 3 times - 42 sts remain.

Or do I do a BO row a dec row a BO row (3 times). I am making the Brittany Jumper #130 by Minnowknits.

Marilynn