Spawn and hit on prefab

I have spawnNext() function that is called Update() function and also run several lines of code. My question is beloved code is right way to spawn prefabs and hit them. Sometimes, spawnNext function waits before called. Because, some prefabs instantiates lately.

 function Update () {
 
     Timer += Time.deltaTime;
     if(spawnedGameobject == null){
         spawnNext();
     }else{
         timeLeftUntilSpawn = Time.time - startTime;
         if(timeLeftUntilSpawn >= secondsBetweenSpawn){
             startTime = Time.time;
             timeLeftUntilSpawn = 0;
             spawnNext();
         }
     }
     //mouse hit or touch on mobile
     if (Input.GetMouseButtonDown(0)) {
             var hit : RaycastHit2D = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.mousePosition), Vector2.zero);
             if (hit != null && hit.collider != null && hit.collider.tag != "Untagged") {
                 if(hit.collider.tag == "num101"){    
                     myScore += 101;
                     myScoreText.text = '' + myScore;
                     Destroy(GameObject.FindGameObjectWithTag(hit.collider.tag));
                     PlayerPrefs.SetInt("CurrentScore", myScore);
                     CheckHighscore();
                 }else{
                     grabScore.push(hit.collider.tag);
                     updateScore(grabScore.length);
                     myScoreText.text = '' + myScore;
                     Destroy(GameObject.FindGameObjectWithTag(hit.collider.tag));
                 }
             }
     }
 }
 function spawnNext(){
 
     // Random Index
     whichNumber = Random.Range(0, generateWeighedNumber.Length);
     whichPosition = Random.Range(0, startPositionXofSpawner.Length);
     // Spawn Number at current Position
     spawnedGameobject = Instantiate(generateWeighedNumber[whichNumber], Vector2(startPositionXofSpawner[whichPosition], 15), Quaternion.identity);
     spawnedGameobject.GetComponent(SpriteRenderer).color = Color(Random.Range(0.5f, 1f),Random.Range(0.5f, 1f),Random.Range(0.5f, 1f),1);
     if(Timer > randomTimer){
             Timer = 0f;
             randomGravitySpeed += 0.1f;
             secondsBetweenSpawn = Random.Range(0.5f, 1.0f);
             randomTimer = Random.Range(30, 60);
             if(randomGravitySpeed >= 1.5f){
                 randomGravitySpeed = 1.5f;    
             }
     }
     spawnedGameobject.GetComponent(Rigidbody2D).gravityScale = randomGravitySpeed;         
 }