VBS scripting question - manipulating dates - vbscript

Question

I have the following code (manipulated some code from a helpful soul out in cyberspace).
What it is meant to do is to zip all .csv files in a directory and name the zip file with the current timestamp.
My problem - I have setup a scheduled task to execute the below code everyday. As you can see, I am going back a day each time the code is executed. Meaning, zipping the file today with yesterday's "day". When it runs on the 1st of every month, I obviously run into a problem. It will grab yesterday's day (which is fine) but the current month. How can I manipulate the code so that it checks if yesterday was the last day of the month and put the correct timestamp for the filename?
Any assistance is greatly appreciated.
strFilepath = "c:\files"
strDestination = "c:\files\completed\" '"#
strExtension = "csv"
strYear = Year(Now)
strMonth = Right("0" & Month(Now), 2)
strDay = Right("0" & Day(Now -1), 2)
strHour = Right ("0" & Hour(Now), 2)
strMinute = Right ("0" & Minute (Now), 2)
strZip = strFilepath & "\" & strYear & strMonth & strDay & strHour & strMinute & ".zip" '"#
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set objFolder = objFSO.GetFolder(strFilepath)
For Each objFile in objFolder.Files
strFileExt = objFSO.GetExtensionName(objFile.Path)
If LCase(strFileExt) = LCase(strExtension) Then
ZipFile objFile.Path, strZip
End If
Next
Sub ZipFile(strFileToZip, strArchive)
Set objFSO = CreateObject("Scripting.FileSystemObject")
If Not objFSO.FileExists(strArchive) Then
Set objTxt = objFSO.CreateTextFile(strArchive)
objTxt.Write "PK" & Chr(5) & Chr(6) & String(18, Chr(0))
objTxt.Close
End If
Set objApp = CreateObject( "Shell.Application" )
intCount = objApp.NameSpace(strArchive).Items.Count + 1
objApp.NameSpace(strArchive).CopyHere strFileToZip
Do
WScript.Sleep 200
set objNameSpace = objApp.NameSpace(strArchive)
If Not objNameSpace is nothing Then
If objNameSpace.Items.Count = intCount Then
Exit Do
End If
End If
Loop
End Sub

Answer 1

Just check Day(now) value. It it = 1, then Month = Month -1.