Updating score within timeframes

I'm looking to update my score once every time a player taps the screen within a certain timeframe.

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. using UnityEngine.UI;
4.  
5. public class uiManager : MonoBehaviour {
6.  
7.     private int score;
8.     public Text scoreText;
9.     // Use this for initialization
10.     void Start ()
11.     {
12.         score = 0;
13.    
14.     }
15.    
16.     // Update is called once per frame
17.     void Update ()
18.     {
19.         if(Time.time > 0.8 && Time.time < 1.2)
20.         {
21.             if(Input.GetMouseButtonDown(0))
22.             {
23.                 score = score + 1;
24.             }      
25.         }
26.         scoreText.text = ""+ score.ToString();
27.            
28.    
29.     }
30. }
31.  

How do I make it so when you press the mouse button down the first time it updates the score and any subsequent times it does nothing?

 

add a boolean "alreadyTapped", set it to false at the start of the time window. Set it to true when the user taps and check "input && !alreadyTapped"

 

Is there a better way to choose multiple time intervals that allow an increase score rather than using many if statements?