Call the purl row after the 6 rows of knit, row 7. Then you would increase on the next knit row, row 8 and on the following rows 16,24,32,40, etc.
You can relax, however, a row or two off in making the increases won't make much difference. Do you knit both sleeves at the same time? I find that that makes it easier to keep the sleeve increases the same on both sleeves.