How do I change the coordinates of the GameObject to the first cube in the generated grid?

I have generated a grid from cubes and I need a way to re position the GameObject with the script GRIDGEN attached to the first cube (top left of the generated grid). I need to do this without moving the grid since the script generates the grid from the centre where the GameObject is.

Thanks.

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class GridGen : MonoBehaviour {
 
     public GameObject cube1;
 
     public int gridWidth = 10;
     public int gridHeight = 10;
 
     public float spawnSpeed = 0;
 
     void Start()
     {
         StartCoroutine(CreateGrid());
     }
 
     private IEnumerator CreateGrid()
     {
         for (int x = 0; x < gridWidth; x++)
         {
             yield return new WaitForSeconds(spawnSpeed);
             for (int z = 0; z < gridHeight; z++)
             {
                 yield return new WaitForSeconds(spawnSpeed);
                 GameObject cube = Instantiate(cube1, Vector3.zero, cube1.transform.rotation) as GameObject;
 
                 cube.transform.parent = transform;
                 cube.transform.localPosition = new Vector3(x, 0, z);
             }
         }
     }
 }