Event Trigger

If I'm understanding, you may have a StartCoroutine(showInfo()) with a 3 seconds yield when pointing. And if you need, stop it when PointerExit.

 void pointing()
 {
   StartCoroutine(showInfoDelay());
 }
 
 IEnumerator showInfoDelay()
 {
   yield return new WaitForSeconds(3f);
   showInfo();
 }

Add a semaphore for avoid multiple calls to the coroutine.

But not sure if I'm understanding the issue X)

EDIT: call "pointing()" when pointing or cliking, up to your code.

I try this all day but, Pointer Enter is just when you put cursor on button .. no click .. and there is no wait :)

Sorry, I missunderstood the Pointer Enter. Hm... the problem is not trigger the coroutine, because you may start the coroutine inside the OnPointerEnter. The problem is when the mouse points out from the button before that 3 seconds. $$anonymous$$aybe you could check if the mouse still is over the button after that 3 seconds. Pseudocode (I can't test today):

 //define a rect
 rect = new Rect(x, x, x, x);
 
 void OnPointerEnter()
 {
    StartCoroutine(infoDelay())
 }
 
 IEnumerator infoDelay()
 {
    yield return new WaitForSeconds(3f);
    check$$anonymous$$ousePosition();
 }
 
 void check$$anonymous$$ousePosition()
 {
    mouse = new Vector2(Input.mousePosition.x, Input.mousePosition.y);
  
    if(rect.Contains(mouse))
    {
       showInfo$$anonymous$$ethod(); //label, window, object....
    }
 }

Is this closer to your solution?

EDIT: add:

 void OnPointerExit()
 {
    StopCoroutine(infoDelay());
 }

I will try tomorrow, but is rectangle good solution ? if i will have 50 buttons ?

In your case, set true pointing in the pointer event:

 using UnityEngine;
 using System.Collections;
 
 public class Timer : $$anonymous$$onoBehaviour 
 {
     private float targetTime = 3f;
     private float timer = 0;
 
     private bool pointing = false;
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () 
     {
         if(Input.Get$$anonymous$$eyDown($$anonymous$$eyCode.A) && !pointing)
         {
             pointing = true;
         }
 
         if(pointing)
         {
             timer += Time.deltaTime;
         }

         if(timer >= targetTime)
         {
             pointing = false;
             timer = 0;
             Debug.Log ("show info");
         }
 
         Debug.Log (timer);
     }
 }

EDIT: after "if pointing", add else { timer = 0; } for reset the timer. And add pointing false OnPointerExit.

Hum... if this is not correct, no have more ideas, sorry haha x)