How did Chandler and Monica became Friends in the first place. And what year did they started being Friends

How did Chandler and Monica became Friends in the first place. Because in thanksgiving 1987 Ross brought Chandler to they house and Monica was still fat and Chandler tall Ross "I don't want to be stuck her with your fat sister" what make Monica lose all her weight and she was upset with Chandler for a year. And what year did Chandler and Monica became Friends in.