I recently saw the second season show where Joe and Helen were trying to celebrate Valentine's Day, and Antonio made his first "WINGS" appearance....but not as a cab driver, but as a waiter in an Italian restaurant.

The following season Antonio became a cast regular as the airport's cab driver. However, I've never seen his first "cabbie" episode.

Was reference made to his earlier job as a waiter, and to his previous encounter with Joe and Helen, or did they just start Antonio's "cabbie career" with no reference to that earlier "waiter" episode?

He said in his fist cabbie episode that the restaurant he worked at was shut down. I guess he got a job as a cab driver and started hanging around the airport and befriended everyone. There were about 10 months between the 2nd season finale and the 3rd season premiere. He must have become a cab driver during that time period. I don't think they ever explained it. He did make a few references to his old waiter job.

I heard Antonio was only supposed to be on one or two episodes, but he was so well-liked by focus groups that the producers decided to make him a series regular. Good move, IMHO.