Here is what I use to timestamp my cubes.
Sub Main
Dim objTrans as Object
Dim objModel as Object
Dim objCube as Object
Dim strModelName as String
Dim strPath1 as String
Dim strPath2 as String
Dim strModel as String
Dim strCube as String
Dim strCubeName as String
Dim varDate as Variant
'*** File names and path(s) ***
strPath1 = "E:\"
strPath2 = "D:\"
strModelName = "ModelName.mdl"
strCube = "ModelCubeName.mdc"
strModel = strPath1 & strModelName
'*** Finds system date and creates new cube name ***
varDate = CVar(Date)
strCubeName = strModelName & Format(varDate,"Medium Date") & ".mdc"
'*** Open model inside Transformer ***
Set objTrans = CreateObject ("CognosTransformer.application")
Set objModel = objTrans.OpenModel (strModel)
Set objCube = objModel.Cubes.Item(1)
'*** Builds Cube ***
objCube.CreateMDCFile
'*** Renames cube ***
FileCopy strPath1 & strCube, strPath2 & strCubeName
End Sub