I have begun.
The yarn is labeled bulky, so I am suing a US J / 6.5 mm hook. At first I thought it was too big because the interlocking seemed loose. I adjusted my tension and my crochet has improved.
In case you forgot the colors I am going to use in this afghan, here they are again…

I was going to write up a pattern, but it is really slowing me down and I have decided there is not much use for it without instruction on how to Interlock Crochet. Oh well, at least I am able to teach the technique now…in-the-round!