I just wanted to share what I figured out today with respect to the canter depart for anyone else who may be having issues with it.
I found that if I get off the horse’s back he picks up the canter when I ask. Yesterday, I had absolutely no problems with the canter depart. Today, I did. What I think is part of the difference is that I was unbalanced today. My saddle pad had shifted, which unbalanced my saddle and put me on the cantle. Maybe yesterday I was balanced enough that I was clear in my request and today I wasn’t. Once Barbara pointed out that I was sitting on the cantle, I changed my approach. I got into two-point just before I asked for the canter. It was more like just not posting in the up position for a stride, but it worked wonders. It makes sense from a biomechanics standpoint as the best time to ask for the canter is when his inside hind leg is coming forward (and outside shoulder is forward and you are rising) – I could be wrong on this, so you may want to look it up, but I remember someone telling me this and it makes sense to me.
So for anyone else having similar problems, try getting off your horse’s back and see if that makes a difference.