Tip: When you get to the top edge of the border, just use the circular needle. Hence the reason i said "leave stitches on circular needle". When you get to the bottom edge, put the live stitches on circular needle and use it as you did the top edge. If your wondering if you can just put them all on a circular...dont. been there done that, dont work. But the top and bottom edges work great with a circular. And the sides work great doing them with dpns(or straights) but there is only a few stitches to work with and straights might be a bit of an overkill in an already stressful situation.
"Be who you are and say what you feel because
those who mind don't matter and those who matter don't mind." - Dr. Seuss