MonoBehaviour.OnServerInitialized  

function OnServerInitialized() {
Debug.Log("Server initialized and ready");
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
void OnServerInitialized() {
Debug.Log("Server initialized and ready");
}
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

def OnServerInitialized():
Debug.Log('Server initialized and ready')