How to make player starts moving after holding a key for certain time only once

Questions & Answers
1

Hi
I am making a 2d game runner like the picture where the first action to only start the game ( after holding down the key player does not have to hold it anymore), player has to hold down a key (lets say G) and after a certain time like 3 seconds the player model starts moving automatically forward on x axis only and up and down on y axis. It is like when you want to start a car engine you have to hold down the switch for like 3 to 5 seconds and then car engines starts to move.

source: HOW TO MAKE A SIMPLE GAME IN UNITY - ENDLESS RUNNER - #1 - YouTube

2

void Start()
{
StartCoroutine(InitMovement());
}

IEnumerator InitMovement()
{
   bool iddle = true;
   float timer = 0;
   float maxTimer = 3;

   do
   {
      if (Input.GetKey(KeyCode.G)
      {
         timer += Time.deltaTime;
         if (timer >= maxTimer) iddle = false;
      }
      else
      {
         timer = 0;
      }
      yield return null;
   }
   while(iddle);
   //START MOVING HERE
}