I recommend doing these exercises twice daily, morning and evening. In the morning, doing these exercises during or after a shower can undo what your sleeping positions may have done, as well as get you ready for your day. And right before bed at night to relax the neck muscles and re-educate the cervical spine on proper movement mechanics. It is also a great way to unwind from a long day and not carry the stress of the day to bed which may affect the way you sleep.
As with all exercises, if there is ANY exasperation of pain, immediately discontinue the stretches/exercises until you can check with Dr. Blue.