You may want to feed him right away but you are best to wait a week for him to settle in. There is no way he was feeding well before you got him so its unlikely he will feed immediately for you.

check out the link starmom pointed out, its probably the best way to house a small snake. Your snake probably needs a better setup to thrive. If he is stressed he may never eat and by the looks of it he hasn't eaten in some time already. From my experience it looks like it may have not eaten in the last 8-10 months.