It doesn't look that thin. You can try feeding it this weekend if you want just does freak out if it doesn't eat.
Make sure you don't handle him for at least a week. Any new reptile should be left alone for the first week so they can settle in. It will be stressful enough for then getting a new home. THey don't need to be stressed out more by getting handled. If you are worried about the wieght I wouldn't handle him until he gets eatting.