Rejoining to work in the round

I’m feeling a little dense today…

I am working on Dill (from Rowan Newsshapes). It is not a free pattern, so I can’t link to it. And I’m not following the directions exactly so hence the question.

Dill is a shrug knit from cuff to cuff. The pattern is written to knit it flat and then seam the arms. You cast off and cast on sts for the front opening. HOWEVER, I knit the first sleeve in the round, switched to flat for the body, and am not about to rejoin in the round for the other sleeve.

The pattern repeat is 6 rows. On the first sleeve I switched from knitting in the round to flat on a RS row (row 3 of pattern). So now I am about to start row 3 on the other sleeve, but find that will give me purl sts on the RS instead of knit sts. Am I doing something wrong that is obvious to all except me? Should I be joining on WS row (like row 2 or 4)? Obviously I should have taken better notes on the first sleeve