Haywain whether he's in an offside position is only relevant when his teammate last played/touched the ball; his position when he becomes active, i.e. is considered offside, is irrelevant to determining offside.
The laws say the offside player cannot challenge an opponent for the ball.
It provides no timescale or advice on when the player can start challenging for the ball again.
I think bester's answer is.... best. Once the defender has the ball under control the offside player can challenge him.
LOTG said:A player in an offside position receiving the ball from an opponent, who deliberately plays the ball (except from a deliberate save), is not considered to have gained an advantage
Surely no timescale is provided because, until a team-mate of the offside player touches or plays the ball again, then the original reason for the player being offside is still there and, since a player in an offside position can't challenge an opponent for the ball, the job's a good 'un
Why invent a 'rule' about opponent's taking two touches / getting the ball properly under control when there is an actual law to follow?