Sorry if you think I misled you, I was just trying to interpret what you wrote. Okay, here's that section -
"Shape neck: Next row: Cast off 10 sts. Pat to end of row. Work 1 row even in pat. "
You do this cast off on a RS row, finish the row, then do the WS row.
"Keeping cont of pat, dec 1 st at neck edge on next 3 rows, then on following 2 alt rows. 17 (20-22) sts. Work 3 rows even, thus ending with WS facing for next row."
So the decs start again on the RS row, dec on the WS, then the RS row. Do the WS row with no decs, Dec on the RS row, plain row for the WS, and dec again on the RS row. That should put all the decs at the neck edge. Then working the next 3 rows would be WS, RS, WS and start the armhole BOs at the beg of the RS row.
sue- knitting heretic