I'm glad you can appreciate my position.....and, I'm also very happy for you that you have a good relationship with your GP.
I do think you are making a wise decision in going down to 20mg. And, truly, that is not the high end of the most common maintenance doses - 10mg is.
Since your levels were still a bit over-range and you are new enough to Graves' that antibodies might still be a factor, 20mg does seem appropriate until you get labs.
Getting labs on Dec. 12th will accurately reflect just what the 20mg accomplished.
Re the course: Look for lesson 6 - conventional treatment options - introduction.....and read page 2 of the anti-thyroid drugs section titled "dosage". You'll find the information to which I refer.
Best of luck to you moving forward - please keep us posted.