Morning Prayer

What are the earliest times in the morning one can start prayer? Please relate answer to sunrise (44 min before Alot Hashachar) and not time of day (6:05). Earliest time for Barchot before Birchot Hshachar, i.e. Limud Torah, etc? Earliest time for Bichot Hashachar? Earliest time for Psukei Dezimra? Earliest time for Shma Ubirchotahah? Many thanks.

Someone who awakes for the day from his night’s sleep can say- even before “Alot Hashachar”- all the Birchot Hashachar including “Birkot Hatorah” with the exception of “Asher Natan Lasechvi Veena”, for which he should wait until “Alot Hashachar”- Ishei Yisrael ch.5, 6 and ch.6, 28. (“Alot Hashachar” is between 72-90 minutes before sunrise and not as stated in your question-Ishei Yisrael ch. 13.) The earliest time for Shma and its Brachot is the hour that a person can recognize his acquaintance from a distance of two meters (in Israel- about 50 minutes before sunrise- Ishei Yisrael ch. 18). Since, however, it is preferable to delay Shmone Esre until sunrise, Shma and Psukei Dezimra should be paced accordingly.