[BerntR]

You shouldn't try to cock it with your right elbow. You should simply let it happen when it happens.

Think of where you want to have your hands at the top (or at the end) of the back stroke. Bring the hands there with a quiet (Yoda says frozen I think) right wrist. One that is level and bent. This motion - the pickup of the club with a quiet right wrist - will cock the left wrist as a "side effect". It is a geometrical necessity.

Keeping the right wrist quiet while during the back stroke is a winner as far as getting in a good position at the top because it promotes a good rhythm. In many ways it's the opposite of deliberately trying to cock the left wrist, something that can be a stroke wrecker.