Make sure the animal has hides. A 20 gallon is going to be a little big for a smaller snake if that is indeed what you are getting. Leave the animal alone until it starts eating no matter how bad you want to go in there and mess with it. Figure out what the breeder was doing as far as feeding goes and copy that. If the breeder was feeding live don't shove FT in its face until you get it consistently eating in your set up.