well I am of the opinion its the same principle as with a bit really .... ask softly and release to the smallest try. I do lots of transitions from walk to back up to forward..... just a few steps at a time or even just one foot, or even just a shift in weight. A lot of it anyway is on weight aids and or leg aids rather than the bridle ...... but it depends on the stage of training you and your horse are at too.
How long have you had the dr cooks ..... are you just changing to bitless ?