engraving

When do you have to get your SBR engraved? Is it before you get the tax stamp, but after certification? Or do you wait until after the stamp gets approved? On a related note, what exactly must be engraved? The name of the trust, the city and state? What if you move?

A friend at work stretched his Christmas budget quite far and bought his son a Henry "Golden Boy" 22lr. He would like to have it engraved but his budget is minimal. Does anyone have any experience with machine engraving firearms? Custom hand engraving is way too expensive and out of the question.