Scene Change after some time when achieving a certain Score C#

Hello everyone, i'm making a simple game where you gather blocks, each block = 1 to score. It's based on the " Roll a Ball " Tutorial. Now here's what i want to do.

I need to change the scene after let's say 5 seconds using " WaitForSeconds " so i can display a " Good Job " Text and Change the Game Scene to the Next level after those 5 seconds.

Here's the script I wrote, i used a " private bool counting = false; " to check if the score was reached.

 using UnityEngine;
 using UnityEngine.SceneManagement;
 using UnityEngine.UI;
 using System.Collections;
 
 public class PlayerControlls : MonoBehaviour {
 
     private Rigidbody rb;
     private int count;
 
     public float speed;
     public float waitTime;
     public Text countText;
     public Text winText;
     private bool counting = false;
 
     void Start () 
     {
         StartCoroutine (changeDelay ());
         rb = GetComponent<Rigidbody> ();
         count = 0;
         SetCountText ();
         winText.text = "";
     }
 
     void FixedUpdate () 
     {
         float mH = Input.GetAxis ("Horizontal");
         float mV = Input.GetAxis ("Vertical");
 
         Vector3 move = new Vector3 (mH, 0, mV);
 
         rb.AddForce (move * speed * Time.deltaTime);
     }
     void OnTriggerEnter(Collider other) 
     {
         if (other.gameObject.CompareTag ("Pick Up"))
         {
             other.gameObject.SetActive (false);
             count = count + 1;
             SetCountText ();
         }
     }
     void Update()
     {
         if (counting) 
         {
             changeDelay ();
             SceneManager.LoadScene ("Level2");
         }
     }
 
     IEnumerator changeDelay ()
     {
         yield return new WaitForSeconds (10);
     }
 
     void SetCountText()
     {
         countText.text = "Score: " + count.ToString();
         if (count >= 1 && !counting)
         {
             counting = true;
             winText.text = "Good Job";
         }
     }
 }

ANY help would be apreciated. Unity is updated to the latest STABLE version, so 5.3.4