[rpappa]

IDK if you're using iterative robot or command base but essentially:

private int start;

public void initialize() {
	start = encoder.get();
	motor.set(speed);
}

public void loop() { //this would be execute in a command not sure in iterative
	if(encoder.get()-start > 500) {
		motor.set(0);
	}
}

Not tested not even written in an IDE so take it with a grain of salt