What is the meaning of this 将？
將 = about to = will soon

"In the evening, the moment the Sun was about to set," [...I suppose the sentence is unfinished]

edit: right, I am reminded that (slightly old-fashioned sense) 將 has the sense of 了, but that is not equivalent to 剛剛. "了" means something similar to perfect tense, but that does not necessarily happen "just before now".