Doctrine & Covenants 36-38
I remember being intrigued when I first heard the following thought and it really makes a lot of sense. It's definitely something to ponder!
"The Lord Himself said that He `knoweth all things, for all things are present' before Him. (D&C 38:2.) We read, too, that `all things are present with me, for I know them all.' (Moses 1:6.) Therefore, God's omniscience is not solely a function of prolonged and discerning familiarity with us-but of the stunning reality that the past and present and future are part of an `eternal now' with God! (Joseph Smith, History of the Church 4:597.)"
(Neal A. Maxwell, All These Things Shall Give Thee Experience, pp. 7,8.)
Read another great talk by Elder Maxwell describing how this principle relates to the doctrine of foreordination.