You will pick up 11 sts ("starting at cuff end of instep, pick up 11 stitches along the left side of the instep by inserting needle in the little knots at the end of the rows
") These are not from the holder.
You will then knit the 11 sts from the last holder (the 11 from the end of the row when you put them on a holder).
Then turn and knit across the 30 sts (11 from holder + 11 you picked up + 8 at toe).
Now you pick up 11 sts along the side (" Pick up 11 sts from the right side of the instep, and K them
Knit the 11 sts from the first holder you put sts on.
You will now have 52 sts. 30 sts from when you turned + 11 you picked up + 11 from holder.
how do I do that when the other needle is still holding the 8 stitches at the toe of the bootie?
You're adding onto the row, so it's right.
I hope this helps a bit. I'm not great at explaining things I haven't done, or am not doing, but sometimes writing it differently can help.