Activate dissolve shader at specific time

I'm trying to trigger/activate the dissolve shader at the specific point (when an object is enabled), but dissolving starts at the beginning of the scene even if the game object is disabled. Game object is disabled at the beginning but the dissolve shader works independently and then when I activate the game object shader is already dissolved. Can anybody help me with this. I believe it has to be an easy solution but I can not figure it out. Below is the code.

Code (CSharp):

1.     Material mat;
2.     public GameObject objectToDissolve;
3.  
4.     private void Start()
5.     {
6.         mat = GetComponent<Renderer>().material;
7.     }
8.  
9.     private void Update()
10.     {
11.         if (objectToDissolve.activeSelf)
12.         {
13.             mat.SetFloat("_DissolveAmount", Mathf.Lerp(0, 1, Time.time / 7));
14.         }
15.  
16.     }

 

What do you mean with this statement?

Code (CSharp):

1. if (objectToDissolve == enabled)
2.  

 

Oh my bad. I was doing some testing. It is...

Code (CSharp):

1. if (objectToDissolve.activeSelf)

 

Code (CSharp):

1. Mathf.Lerp(0, 1, Time.time / 7)

The third parameter of the Lerp function should be a float betwen 0 and one.
However, about Time time, the doc says: