The general rule-of-thumb is to give them one to two weeks to acclimate to their new surroundings, before trying to feed them. Some people end up with a very laid back snake that doesn't mind eating right away...some snakes take several weeks before they are comfortable enough to eat.

I would say, wait a week...with NO interaction with your snake at all except to provide fresh water. Then observe the animal to see how it is settling in. If it continues to show signs of nervousness or constantly balling up whenever you're near...give it another week of isolation. If it seems comfortable with you, then go ahead and try to feed it.