You can visit at any time, as long as you leave the National Park by 9pm. If you’re looking for some spectacular photo opportunities, visit the Pinnacles at sunset. You can then explore the area after dark. But please remember to look up as there are some truly stunning views of the Milky Way to be seen from here.
If you don’t feel comfortable exploring the park by yourself after dark, you can always join a guided tour, which is often the best way to see all the sights.