Wait For Seconds

i want the enemy to wait 2 seconds before reducing the health by 1 point every 2seconds while attacking but it wait for the fist time. and then just drop down from 10 to 0 after it:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.AI;
 
 public class ZombieAI : MonoBehaviour
 {
     public float stoppingDistance;
 
     NavMeshAgent agent;
 
     GameObject target;
 
     Animator animator;
 
     int Health = 10;
 
     // Start is called before the first frame update
     void Start()
     {
         animator = GetComponent<Animator>();
         agent = GetComponent<NavMeshAgent>();
         target = GameObject.FindGameObjectWithTag("Player");
     }
 
     // Update is called once per frame
     void Update()
     {
 
         float dist = Vector3.Distance(transform.position, target.transform.position);
         if(Health == 0)
         {
             animator.SetLayerWeight(2, Mathf.Lerp(animator.GetLayerWeight(1), 0f, Time.deltaTime * 13f));
             animator.SetLayerWeight(1, Mathf.Lerp(animator.GetLayerWeight(1), 1f, Time.deltaTime * 13f));
             //DestroyObject(gameObject);
         }
         else
         {
             if (dist < stoppingDistance)
             {
                 StopEnemy();
                 animator.SetLayerWeight(1, Mathf.Lerp(animator.GetLayerWeight(1), 1f, Time.deltaTime * 13f));
                 StartCoroutine(WaitAndDie());
 
 
             }
             else
             {
                 GoToTarget();
                 animator.SetLayerWeight(1, Mathf.Lerp(animator.GetLayerWeight(1), 0f, Time.deltaTime * 13f));
 
             }
         }
     }
     void GoToTarget()
     {
         agent.isStopped = false;
         agent.SetDestination(target.transform.position);
     }
     void StopEnemy()
     {
         agent.isStopped = true;
     }
 
     IEnumerator WaitAndDie()
     {        
             Debug.Log(Health);
             yield return new WaitForSeconds(3);
             ReduceHealth(1);
     }
     void ReduceHealth(int S)
     {
         Health -= S;
     }

}