If you don't have a Guru Rinpoche initiation, then you can visualize Guru Rinpoche either above your head facing the same way you are or in the sky in front of you facing you. Shenphen Dawa Rinpoche, H.H. Dudjom Rinpoche's son, says either is OK.
In a recent teaching given by Shenphen Dawa Rinpoche on Sang, he stated that you can also visualize yourself as any yidam that you are practicing instead of Guru Rinpoche if you would like. This would mainly be the case if for example you were engaged in a traditional 4 session per day yidam retreat and sang was being done between sessions. He went on to say the main point of the self visualization is that you feel the resplendence and power of the deity before making the offerings, since one is offering to many classes of beings in order to pay back karmic debts.