Introduction: Shacharit: When To Begin

B'di'avad, you can say shema and amida as early as 72 minutes before sunrise (alot ha'shachar).  You can put on tefilin and tzitzit/talit even earlier, although you may not say the blessings over them until “mi'sheyakir”—which is later than you can say shema and amida!  (See above.)