I have an outlook macro that reads the all the Subject lines of all unread emails.

Sub ReadMails()
    Set objOutlook = CreateObject("Outlook.Application")
    Set objNamespace = objOutlook.GetNamespace("MAPI")
    Set objFolder = objNamespace.GetDefaultFolder(olFolderInbox)
    Set objFolderSrc = objFolder.Folders("My Own Folder")

    Dim Subjects() As String
    ReDim Subjects(1 To 1) As String
 
    Set colItems = objFolderSrc.Items
    Set colFilteredItems = colItems.Restrict("[UnRead] = False")

    For Each objMessage In colFilteredItems
        Subjects(UBound(Subjects)) = objMessage.ConversationTopic
        ReDim Preserve Subjects(1 To UBound(Subjects) + 1) As String
    Next
End Sub

Instead I need to read the emails that have come between current time and 8 AM in the morning of the same day.

How do I add that filter?

olFolderInbox is the folder where all received emails go to. This is the root inbox folder. This is not a concern; that part works.