A yo is just wrapping the yarn around the needle and you're supposed to do that, then knit into the cast on stitch. You could do a kfb increase though and it may not make a difference at the beginning here. Later on when the lace pattern is established, it would mess it up. Also you can just CO 2 sts to begin with, that won't be noticeable either and will still make a skinny pointed beginning.
sue- knitting he