Final answer:
According to the "cosmic calendar," the first flower would have bloomed in the evening of December 31.
Step-by-step explanation:
According to the "cosmic calendar," the first flower would have bloomed in late December, more specifically, in the evening of December 31. The concept of the "cosmic calendar" compresses the entire timeline of the universe into a year, with the Big Bang occurring at the start of January 1 and human emergence happening at the end of December 31. Therefore, the first flower blooming would have occurred just before human emergence.