Another day of spinning and now my green yarn just needs to be over dyed.
Everything went pretty much as I predicted. I got about a bobbin and a half of singles from my roving. I skeined them on my niddy noddy and discovered that I had about 1170 yards.
So I divided this number by 2, since my niddy noddy makes 2 yard skeins, and then by 3. This gave me the number of wraps of the skein I needed to get into each ball. I put the skein on my swift and counted off the rotations of my swift as I wound the singles into center pull balls.
Finally I plied my 3 singles together and got 396 yards of finished 3 ply.
Now I just need to give my yarn a good whack or two and stick it in the microwave with a bit more blue dye.