Mangala arati must be done in nightgown. After Mangala arati, then bathing is done and dressing. 3:30 is too early for holding Mangala arati. The deities should be given sufficient rest. The standard time is 1 1/2 hours before sunrise, so we may say 5 am is a good time for holding arati.
Letter to Himavati, 26 December, 1971