Exhale is relaxed with no control at all. If the inhale comes via the nose then the exhale should exit the nose. If the inhale comes through the mouth then the exhale must travel out the mouth. Exhale and inhale need not be the same duration. In short don't stop at the top of the breath or at the bottom.
Breathing is one continuous loop.
With your palm just touching your skin, start from the very center of the top of your head and gently pass down the center line of your body to your groin. Do this slowly for 3 repetitions. This will get a good downward flow for you to assist with your dropping. Tune in fully to your feeling and allow it to be there and grow. Let it percolate.