Delay light on held down button

Hello beautiful answering community! Once again, could be a noob question from a beginner in coding, but I'm trying to program a fireball to appead when the right mouse button is held down. I managed to do that, and when the right mouse button is held, the particle emitter and light source appear. However how would I script the light to be delayed a few seconds? (The light has a different script to the flames) This is the script for the light:

function Start () { light.enabled = false; }

function Update() {

if(Input.GetMouseButtonDown (1))

     light.enabled = true;  
      
 else if (Input.GetMouseButtonUp (1))
 light.enabled = false;
 }

Thanks in advance for your help! :)