Edges of the Sabbath

"We should jealously guard the edges of the sabbath. Remember that every moment is consecrated, holy time." Testimonies for the Church Vol.6, p.355,356 E.G.W.
...from even unto even, shall ye celebrate your sabbath.
Leviticus 23:32
And the evening and the morning were the first day.
Genesis 1:5 So the "day" began at sunset

And which "day" is the Sabbath?
But the seventh day is the sabbath of the LORD thy God:
in it thou shalt not do any work,
Exodus 20:10