Shaping Arm Holes

I am making a sleeveless turtleneck and the instructions say “Bind off 3 sts at beginning of next 2 rows”.

It sounds like what it’s saying is bind off 3 at the beginning of the row then finish the row. Flip to the wrong side and bind off 3 at the beginning of the row then finish the row…

But if I did that then wouldn’t one armhole be slightly higher than the other? Am I supposed to bind off at the beginning AND end of the row?

You always bind off at the beginning of rows because if you try to bind off at the end, your yarn will be in the wrong place.

Just follow the pattern. Most sweaters are made this way, and the few stitches extra on one armhole make no difference whatsoever.