Help for ballerina

I would love to have some advice on how to train for the ballerina move. I know that there is a certain amount of mobility and flexibility that is needed in order to get the pole where it needs to be or should I say where the arm needs to be. What types of exercises if any should I be doing to help get me closer? Right now when I reach back I can get the pole where it sits in between forearm and elbow crease. Any suggestions would be super helpful. Thanks in advance