unity how to make a delay untill you can shoot again

public Transform firePoint;
    public GameObject bulletPrefab;
    public float bulletForce;
    public float fireRate = 0.5F;
    private float nextFire = 1.5F;

    private void Update()
    {
        if (Input.GetButtonDown("Fire1") && Time.time > nextFire)
        {
            nextFire = Time.time + fireRate;
            Shoot();
        }
    }

    void Shoot()
    {
        GameObject bullet = Instantiate(bulletPrefab, firePoint.position, firePoint.rotation);
        Rigidbody rb = bullet.GetComponent<Rigidbody>();
        rb.AddForce(firePoint.forward * bulletForce, ForceMode.Impulse);
    }