Toggling a Texture Overlay every 2 seconds?

I have made a very simple script to overlay a camera texture I made to give my game a found-footage style. However, I have a little “REC” icon in the corner of the overlay. I made an overlay with the recording sign in the top right, then another overlay, which is the same, but does not have the recording sign. I want these two textures to swap every two seconds, to give the impression of a blinking REC sign. I had a go at making a script for this but cannot find a good way to do it. The script is a little unfinished as I’m making this at quarter to 12 but I know that the way I am going about this is incorrect)

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

public class Overlay : MonoBehaviour 
{
	public Texture overlay;
	public Texture overlayWithRec;
	private bool isRecOn = true;

	void Start ()
	{
		isRecOn = true;
	}

	void OnGUI()
	{
		if (GUI.DrawTexture (new Rect (0, 0, Screen.width, Screen.height), overlay)) 
		{
			StartCoroutine (Blink ());
		}
	}
	IEnumerator Blink()
	{
		isRecOn = !isRecOn;
		if (isRecOn == false) 
		{
			overlay.enabled = true;
			overlayWithRec.enabled = false;
		}
	}
}

I would recommend using a UI Image with animation.
The enabled property of the Image component is animatable, as well as the color and other properties.