Down the Lane

I am knitting a baby's shawl. Could anyone tell me what this means
Row1 and every alt

Row 2 k1 (yfwd k1) 8times (17)sts

Row 4 k1 (yfwd k2) 8times (25)sts

Row 6 k1 (yfwd k3) 8times (33)sts

Cont in this manner, working 1 st more between each yfwd and.
CHANGING TO 4 1/2 MM CIRCULAR NEEDLE when required, until the foll row has been worked k1 (yfwd k44) 8times (361 sts)

THe question is. WHEN DO I CHANGE TO THE CIRCULAR NEEDLE

Thank you

Fish ponds wife. Wendy

When it gets to tight to fit 'ordinary needles. I would say

Wendy
Many Thanks.
at least she has stopped asking me
Bob