How do you advance the timing

I have a 2004 lexus ES330. I just had the catallitic converter and sensor replaced. Now the car had another code that said the timing was in retard. How do you advance the timing? Is this done through a computer

I had the timing belt and water pump changed at 90,000 miles and everything was ok then. Now that the 1st converter near the exhaust manifold was changed this is what happened