There is nothing to worry because they are new to your tank. Discus are usually very skittish in the beginning but will swim around your tank after a while. I had some discus hiding for months (eating the food then hiding again)
However, where is the location of your tank? Is it in a busy area? Are there children playing around? Keep those factors in mind. Because you would want a stress free environment for discus or else they get stressed.
They will usually get used to your tank but check them out frequently. Keep going infront of them. But don't scare them. If they are very uncomfortable around you then leave, come back again later. Why? Because they will firstly associate you with food and secondly when you are coming again and again and they are not harmed or threatened, they will consider your approach to be safe. Not only yours but anyone coming towards them. And yes, turn off the lights for the time being or keep it very low.