Answered by Shaykh Faraz Rabbani
Does one go into ruku’ by first dropping the hands to the sides? How exactly are the hands placed on the knees? Should the knees be used as support or not? Should the knees be grasped? Are the fingers to remain straight (not bent) on the knees? Are the fingers to be kept apart on the knees?
The optimal way to go into bowing position is to release one’s hands only as one starts bowing, and to then place them on the knee. One grasps the knee with one’s outstretched fingers, which should ideally be pointing down, so that they too as in the direction of the Qibla. [Ibn Abidin]