Reading Hyperspace, by Michio Kaku, a popular account of higher physics.  I have just gone through the dimensions to 5th level.  He started with Flatland: a Romance of Many Dimensions by a Square in the 2nd dimension.  The 4th dimension adds time.  The 5th dimension adds light.  Not a great description of time as a dimension but hints at how it would be looking in from the 4th dimension, seeing all perspectives as one, kind of like a cubist painting.

My best guess if that you are most likely to enter the 4th dimension as he describes it by riding the now moment.