rotating a prefab before it instantiate

Unity Engine
1

So I have some spheres in 2D.
I want them to be rotated before they instantiate, because they have a velocity applied to them and I want them to go in random directions.
Right now nothing happens, but if I was to take transform.Rotate(new Vector3(0, 0, Random.value * 360) * Time.deltaTime); and stick it into void update they are going to spin around themselves.
Why is this rotation not applied to the orbPrefab?

private float forcef = 150;
private Rigidbody2D orb;

private void Awake()
    {
        orb = GetComponent<Rigidbody2D>();
        orb.velocity = transform.right * Time.deltaTime * forcef;
    }

private void spawnOrb()
    {
        GameObject orb = Instantiate(orbPrefab) as GameObject;
        transform.Rotate(new Vector3(0, 0, Random.value * 360) * Time.deltaTime);
        a.transform.position = new Vector3(0, Random.Range(-4,4), 0);
    }
2

You are rotating the spawner instead of the orb
Try changing

    private void spawnOrb()
        {
            GameObject orb = Instantiate(orbPrefab) as GameObject;
            transform.Rotate(new Vector3(0, 0, Random.value * 360) * Time.deltaTime); //this
            a.transform.position = new Vector3(0, Random.Range(-4,4), 0);
        }

For this

    private void spawnOrb()
        {
            GameObject orb = Instantiate(orbPrefab) as GameObject;
            orb.transform.Rotate(new Vector3(0, 0, Random.value * 360) * Time.deltaTime);//for this
            a.transform.position = new Vector3(0, Random.Range(-4,4), 0);
        }

You can also add the rotation to the Awake

private void Awake()
    {
            transform.Rotate(new Vector3(0, 0, Random.value * 360) * Time.deltaTime);
        orb = GetComponent<Rigidbody2D>();
        orb.velocity = transform.right * Time.deltaTime * forcef;
    }