I know what it's like to anticipate the canter. My instructor used to say "ok pick up the canter when your ready." it was the WRONG phrasing. I'd continue walking adjusting my reins, trying to get bend, over analyzing and procrastinating... until she went "uhh... you gonna canter? I'm falling asleep over here.. :)"
The only way to eliminate that is to canter over and over on a horse you trust. Ideally if you are trotting, you'd sit the trot right before you canter. If it's easier for you, you could try practicing walk to canter transitions instead.
you'll have to fake the confidence until you make it.. but the good news is just by doing it over and over you're going to get better.
Re: any of my advice - Happy to give my two cents, but not an expert... just a girl who loves riding horses!