How to set up the values of the variables after the object is instantiated

I am a beginner in unity3d and programming so i need a bit help with this ... I am making a tetris game for exercise and i have 2 objects 1 is cube (not in scene atm) and the other is manager on the script in manager i use :

Instantiate(cube,new Vector3(xPosition, yPosition , -3),Quaternion.identity);

and the cube appears and everything is fine ... now i want to make a function on the script of the cube that returns its position for the matrix to work, I made transform.localscale(x,x,1) in the void Start () of the cube and that works on the screen ... and then i want to make the new function :

public int VratiMatricuY (float krajY, float pos) { int suma = 0; krajY = krajY + transform.position.y; // total length to the the floor

     for ( float i = 0 ; i < krajY ; i = i + transform.localScale.y ) 
     {
         suma = suma + 1;

     }
     return suma;
 }

and my question is how to force this function to have the exact localscale of the same cube i created and the position of same.... i am getting 0 0 0 for position and 1 1 1 for the scale because those are the values of the cube before the cube is instantiated??