Question Instantiate a single object

This is my Code. I wanna spawn one Objekt but after TimeToSpawn its Generate Infinity Clone. Can help my anyone? I try it with WaitForSeconds but its make no difference.

Code (csharp):

1.  
2.     [SerializeField] float TimeToSpawn = 7f;
3.     [SerializeField] Transform[] spwanlokation;
4.     [SerializeField] GameObject[] SpawnPrefab;
5.     [SerializeField] GameObject[] SpawnClone;
6.     float timer = 0f;
7.  
8.  
9.     // Start is called before the first frame update
10.     void Start()
11.     {
12.      
13.     }
14.  
15.     // Update is called once per frame
16.     void Update()
17.     {
18.         timer += Time.deltaTime;
19.         if(timer > TimeToSpawn)
20.         {
21.             Spawny();
22.         }
23.  
24.  
25.     }
26.  
27.     IEnumerable SpawnControl()
28.     {
29.         yield return new WaitForSeconds(400F);
30.     }
31.  
32.     public void Spawny()
33.     {
34.         SpawnClone[0] = Instantiate(SpawnPrefab[0], spwanlokation[0].transform.position, Quaternion.Euler(0, 0, 0)) as GameObject;
35.     }
36. }

 

So what @MelvMay is saying, is that you should reset the timer to zero after you spawn, or else it'll always be greater than TimeToSpawn. That's basically how countdowns work in programming.