Keep working on your third eye. Four days is really not enough; you should aim for at least 40. I also recommend visualization exercises. One thing that has helped me a lot in visualizing the aura is to imagine a white aura around me. If it helps, use a light to simulate that of your aura. It should be easier.
If you can, work on both chakras, because the third eye always depends on the sixth chakra, so it is useful to work on it. Otherwise, finish the third eye first and then, after forty days, start on the sixth chakra.