How to restrict a button for a second

I know I kind of asked this question one time, but no-one answered me correctly. Firstly Heres my script

 var targetScript : ChangeSprite;
     var AcceptInput : boolean = true;
     private static var score : int = 0;
     var guiScore : GUIText;
 
 
 function Start ()
 {
 guiScore.text = "Score: 0";
 }
 
 
 function OnMouseDown () {
 if(!AcceptInput)
 {
 return;
 }
 AcceptInput = false;
 
 
 targetScript = GameObject.Find("Shape").GetComponent(ChangeSprite);
 
 
 GameObject.Find("Shape").GetComponent(ChangeSprite).enabled = true;
 Debug.Log("Clicked");
 
 if(targetScript.spriteRenderer.sprite == targetScript.diamond) {
 AcceptInput = true;
 score += 1;
 guiScore.text = "Score: " + score;
 }
 
 
 else{
 Debug.Log("Wrong Answer!");
 }
 
 }
 
 function OnMouseUp () {
 AcceptInput = true;
 GameObject.Find("Shape").GetComponent(ChangeSprite).enabled = false;
 }

and the script that is being enabled :

 var diamond : Sprite;
 var circle : Sprite;
 var triangle : Sprite;
 var square : Sprite;
 var number : int;
 var spriteRenderer : SpriteRenderer;
 
 function OnEnable() {
 
 spriteRenderer = gameObject.GetComponent(SpriteRenderer);
 
 number = Random.Range(1,5);
 
 if(number == 1) {
 spriteRenderer.sprite = diamond;
 }
 
 else if(number == 2) {
 spriteRenderer.sprite = circle;
 }
 
 else if (number == 3) {
 spriteRenderer.sprite = triangle;
 }
 
 else {
 spriteRenderer.sprite = square;
 }
 
 
 }
 
 function OnEnable() {
 
 spriteRenderer = gameObject.GetComponent(SpriteRenderer);
 
 number = Random.Range(1,5);
 
 if(number == 1) {
 spriteRenderer.sprite = diamond;
 }
 
 else if(number == 2) {
 spriteRenderer.sprite = circle;
 }
 
 else if (number == 3) {
 spriteRenderer.sprite = triangle;
 }
 
 else {
 spriteRenderer.sprite = square;
 }
 
 
 }

What the script does is OnMouseDown, it enables a disabled script which changes an object's sprite. And if the sprite is the correct answer, it would add a score. If not, Debug.Log("wrong Answer!") I used the accept input thing because if I don't it would play through the sprites non stop because the script wouldn't be disabled. But the thing is, if I press the button, it would add the score before the sprite would even be displayed on the screen, so I want to make a restriction so that you can only press the button and the button can only work when the actual sprite is displayed. Does anyone have any Real ideas? Thank You