Remember this forum is mainly americans ... its their bedtime at the moment which is why you havent got any further replies
I have found in the past that damsels can be quite scared for the first week or so, they will come out, but if you move too close to the tank, or make sudden movements, they tend to quickly hide.
Did you get frozen or live brine shrimp? I dont think they are the best fish food, but will be ok for a bit i suppose, the others will all have good ideas on what is best to feed him.