U COULD JUST WAIT TILL THE LAST SECOND HOLDING R2 RHEN UNLEISH.BUT I LIKE TO USE SUPER CANCEL (R1 AND R2).
IF U GO INTO TRAINING AND SWING IN LOADS OF BALLS FOR LONG ENOUGH U WILL MASTER IT.BUT I WARN U,ITS A DIFFERENT STORY DOING IT ON THE PITCH.
TIP. use retry,play again in training this will save u loads of time and u can keep trying till u score.also dont hold it in too much.try to just nudge it to the side at the last second.