Selection.PreviousRevision (Word)

Locates and returns the previous tracked change as a Revision object.

PreviousRevision (Wrap)

Wrap: True to continue searching for a revision at the end of the document when the beginning of the document is reached. The default value is False.

Selection.EndOf Unit:=wdStory, Extend:=wdMove 
Set myRev = Selection.PreviousRevision 
If Not (myRev Is Nothing) Then MsgBox myRev.Date