How did Chandler and Monica became フレンズ in the first place. And what 年 did they started being フレンズ

How did Chandler and Monica became フレンズ 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 here with your fat sister" what make Monica lose all her weight and she was upset with Chandler for a year. And what 年 did Chandler and Monica became フレンズ in.