I'd leave it a week before feeding/handling. Won't hurt it to settle in. Then again i've offered them food as soon as I've had them if I thought they'd take it. But generally is best to leave them a bit, especially if it's been in the post.
Learn to read your snake first. Leave him the heck alone until you can visibly see hes settled in. You'll learn soon enough when he does and doesnt mind being handled.
I've got a little rock cave thing and i have a astrotriff like substrate its green like carpet. He also has a a setup like fake rocks on the warm side they aren't real so they dont get hot. He ll come out when its dark in my room but once he sees me hes back in his cave or rocks.