The other thing about trying to use every bit of a hank of yarn like this involves a postal scale. My postal scale is very important in my crochet
designing since I use it to weigh yarn and projects to give you the yardage used.
For this project, I weighed the yarn to determine when I had reached the halfway
point of the yarn (actually 45 grams) then I knew that I had enough to get to the opposite point and a little bit extra for trim.
If you're a designer, even if you
don't design for the purpose of selling patterns, I absolutely recommend a postal scale.