using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System;

public class TimeMgr : MonoBehaviour 
{
    private static TimeMgr mInstance;
    public static TimeMgr Instance
    {
        get
        {
            return mInstance;
        }
    }

    public delegate
 
 void Interval();
    private Dictionary<Interval, float> mDicinterval = new Dictionary<Interval, float>();

    public void AddInterval(Interval interval,float time)
    {
        if (null != interval)
        mDicinterval[interval] = Time.time + time;
    }

    public void RemoveInterval
 
(Interval interval)
    {
         if (null != interval)
         {
             if (mDicinterval.ContainsKey(interval))
             {
                 mDicinterval.Remove(interval);
             }
         }
    }


    // Awake is called when the script instance is being loaded.
    void Awake() 
    {
        mInstance = this
 
;
    }

    void Update()
    {
        if(mDicinterval.Count > 0)
        {
            List<Interval> remove = new List<Interval>();
            foreach(KeyValuePair<Interval,float> KeyValue in mDicinterval)
            {
                if (KeyValue.Value <= Time.time)
                {
                    remove.Add(KeyValue.Key);
                }
            }
            for (int i = 0; i < remove.Count;i++ )
            {
                remove[i]();
                mDicinterval.Remove(remove[i]);
            }
        }

    }
}

Test

void Start()
    {
        TimeMgr.Instance.AddInterval(TestCall1, 3f);
    }
void TestCall1()
    {
        Debug.LogError("TestCall_1");
        TimeMgr.Instance.AddInterval(TestCall2, 2f);
    }

    void TestCall2()
    {
        Debug.LogError("TestCall_2");
        TimeMgr.Instance.AddInterval(TestCall1, 5f);

    }