Mrs. White has in two visions been shown something in regard to the time of the commencement of the Sabbath. The first was as early as 1847, at Topsham, Me. In the vision she was shown that to commence the Sabbath at sunrise was wrong. She then heard an angel repeat these words, "From even unto even shall ye celebrate your Sabbaths."

In the first vision we were directed to the word of God by the words "From even to even;" but on astronomical grounds, it was then decided that even was six o'clock. In the second, exactly the same words were used, and we were more especially directed to the word of God, which when examined conclusively establishes sunset time. This settled the matter with Bro. Bates and a few others, and general harmony has since prevailed on the question. James White, RH Feb 25, 1868

It shall be unto you a sabbath of rest, and ye shall afflict your souls: in the ninth day of the month at even, from even unto even, shall ye celebrate your sabbath. Lev 23:32 

But at the place which the LORD thy God shall choose to place his name in, there thou shalt sacrifice the passover at even, at the going down of the sun, at the season that thou camest forth out of Egypt. Deu 16:6