Invoke

InvokeScript

using UnityEngine;
using System.Collections;

public class InvokeScript : MonoBehaviour 
{
    public GameObject target;
    
    
    void Start()
    {
        Invoke ("SpawnObject", 2);
    }
    
    void SpawnObject()
    {
        Instantiate(target, new Vector3(0, 2, 0), Quaternion.identity);
    }
}

InvokeRepeating

using UnityEngine;
using System.Collections;

public class InvokeRepeating : MonoBehaviour 
{
    public GameObject target;
    
    
    void Start()
    {
        InvokeRepeating("SpawnObject", 2, 1);
    }
    
    void SpawnObject()
    {
        float x = Random.Range(-2.0f, 2.0f);
        float z = Random.Range(-2.0f, 2.0f);
        Instantiate(target, new Vector3(x, 2, z), Quaternion.identity);
    }
}