unsigned long start = 0;
bool stop = false;

void setup() {
  pinMode(2, OUTPUT);
  start = millis();
}

void loop() {

  if ( (!stop) && ((millis() - start) > 2000)) {
    digitalWrite(2, HIGH);
    delay(100);
    digitalWrite(2, LOW);
    delay(100);
    stop = true;
  }

}