How to spawn all humans at once and activate then with time?

What I am trying to do is to spawn humans that will simply pass by my charactarter, I have wrote a script However constant spawning causes some flickering in Oculus, thus I want to redo it the way that all humans will be spawned at once and activated with time, but I am worried that humans will overlap each other and it will cause problems. Will be thankful if you could recommend me an elegant way to solve this problem.

         void Spawn()
         {
                 Debug.Log("Spawn Function Activated");
                 RandomHuman = Random.Range(0, humans.Length);
                 GameObject spawnedPrefab = Instantiate(humans[RandomHuman], new Vector3(transform.position.x, 0, transform.position.z), transform.rotation);
              }
     
         void Start()
         {
             InvokeRepeating("Spawn", 0f, 3f);
         }
     
     
         void Update()
         {
             SpawnWait = Random.Range(SpawnLeastWait, SpawnMostWait);
     
         }