The direct answer to your direct question of "Must I record each buy" is "No". Your direct answer to your direct question "Can I aggregate all purchases into a single one and date it with the last buy's date for long/short gain determination" is "Yes."
Tell TurboTax no 1099-B was received (I assume) and enter the word "various" in the date acquired box. TT will ask "all purchased before 12/31/2016?" and you answer "Yes".
