After completing the turtleneck, switch to 8mm needles. Raglan is knitted with alternation of increase and no increase rows, total amount of rows for size S is 22 (around 24 cm / 10 inches).
25 cm is an average length of a raglan length for a S/M size sweaters.
In my pattern I made raglan lines as 2 purl (P2) stitches. Since I’m a complete beginner such raglan style makes it easy to emphasize the boundaries between the front, back, and sleeves and simply see my raglan lines.
So, divide the 56 stitches into 4 sections: 10 stitches per sleeve and 14 for the back and front. Place markers around raglan stitches and the start of the row. My sleeves, front and back will grow the same amount of stitches.
I chose make one increase method throughout the pattern and my increases are made on either side of the raglan line markers. One increase comes before the marker and one after the marker, remember in between markers I have 2 purl stitches. On my increase row I will be adding a total of 8 stitches (i.e. 2 increases around 4 raglan lines).
So if I start with 10 stitches for the sleeve and 14 for the back/front after the increase row I will have 12 stitches for each of the sleeves and 16 for the back / front and 8 purl increase stitches which are my raglan lines.
More detailed:
Start: I have picked up 56 stitches from the turtleneck on 8mm needles.
1st increase row (odd): P2 (raglan line), M1R (make one right) increase, knit 10 stitches of the sleeve, M1R, P2 ( raglan line), M1L, knit 14 stitches of the front, M1R, P2 ( raglan line ), M1R, K10 of the sleeves, M1R, P2, M1R, K14 of the back, M1R. We stopped with increase before the raglan line, on the second row we start with P2.
Total stitches after increases and including the raglan = 2( raglan) + 12 (sleeve) + 2 (raglan) + 16 (front) + 2(raglan) + 12 (sleeve) + 2 (raglan) + 16 (back) = 64
2nd no increase row (even) : P2, K12, P2, K16, P2,K12, P2, K16.
Repeat this rapport as follows: all odd rows are increase rows all even rows are no increase rows.
3rd row: M1R increase on either side of the 2P raglan stitches
4th row: no increase and so on.
Total of 22 rows will measure up to about 24 cm (10 inches). This is a standard raglan line length for women