If imitation is the sincerest form of flattery, then ATT, Verizon and Sprint must all hold T-Mobile CEO John Legere in high regard. OK, so that’s definitely not true but it is true that Legere and his underdog mobile carrier have been the major trendsetters in the wireless industry over the past year. FierceWireless’s Roger Entner has put together a nice timeline chronicling how T-Mobile’s moves over the past year have forced its rivals’ hands by pushing them to follow T-Mobile’s new initiatives with similar ones of their own. The action really starts in July 2013 when T-Mobile first unveiled its Jump smartphone early upgrade plan that all three of its rival carriers rushed to copy. Entner also notes that