Pattern Help - Stockinette and Increasing

I’m working on a baby sweater and I’m confussed by their language, specifically for the sleeves. The instructions are:

Sleeves

Cast on 17 (21-21) sts. Knit 3 rows (garter st), noting 1st row is WS and inc 1 st at center of last row. 18 (22-22) sts.

Proceed in stocking st, inc 1 st each end of next and every following 6th (6th-4th) row until there are 26 (30-34) sts.

Cont even for 7½ (8½-9½)" [19 (21.5-24) cm] total length, ending with a purl row. Cast off.

And the questions are:

  • When I “proceed in stocking” (stockinette) am I starting that row, which would be the 4th row of the sleeve, with a knit or a purl to begin stockinette?

  • Where it says, "inc 1 st each end of next and every following 6th row . . . " does that mean that I increase in the next row I knit, which would be the first row of stockinette, or do I knit 5 rows of stockinette and then increase for the first time on the 6th row?

Thank you for your help!!

Start row 4 with a knit row. For this pattern, the even numbered rows are the RS rows and the odd numbered rows are WS. Increase at each end of this row, row 4 and every following 6th row. So increase on row 4, 10, 16 etc until you have the required number of sts.