Yes. Don't accept a sloppy transition. Ask from the trot you want, and that's the trot he's going to transition from. It may take most of your ride to get it, most likely because it will take some time to get him back to your good trot. So you may not be able to do much cantering.
Something to remember is that trot to canter transitions are actually very hard on a horse, much harder than a walk to canter transition. Think of the gait, how the legs are moving at the trot, and then at the canter. Then the walk. See how similar the walk is to the canter?