LIned up offsides

[Warrenkicker]

You say "lined up offsides". I assume (there's that word) that you mean they were lined up in the neutral zone but not in any three-point stances. Like KWH says you can flag it any time after the RFP and the snapper has his hand on the ball. But were the offense to line up in a stance with a hand on the ground then they can't move and can't back out of the neutral zone. You may give them a chance once to get back before they get set but after they are set they can't move and thus can't "unencroach". Flag them as soon as you can so you don't get other things happening like defensive encroachment also.