Vector3.Lerp to Multiple locations

I'm trying to make script where I can move a object accurately between 4 locations. I've decided to use Vector3.Lerp however I can't seem to make it transition between one larp to another. I've posted the code bellow. when I've got this working I'm hoping to build upon the script and build something similar to the opening scene of the Ocarina of Time or the ending of Portal.

Hope you can fix this thanks!

Code:

 #pragma strict
 
 var start : Transform;
 var check1 : Transform;
 var check2 : Transform;
 var check3 : Transform;
 var i = 1;
 
 function Update() {
 var smooth = 2.0;
     if(i == 1){
     transform.position = Vector3.Lerp(check1.position, check2.position, Time.deltaTime * smooth);
     
         if(transform.position == check1.position ){
         i++;
         }
     }
     
     if(i == 2){
     transform.position = Vector3.Lerp(check1.position, check2.position, Time.deltaTime * smooth);
     
         if(transform.position == check2.position){
         i++;
         }
     }
     
     if(i == 3){
     transform.position = Vector3.Lerp(check2.position, check3.position, Time.deltaTime * smooth);
     
         if(transform.position == check3.position){
         i++;
         }
     }
     
     if(i == 4){
     transform.position = Vector3.Lerp(check3.position, start.position, Time.deltaTime * smooth);
     
         if(transform.position == start.position){
         i = 1;
         }
     }
     
     
 }