After the reference is set, Word variables can be declared with the correct (Word) variable type.
Sub WordEarlyBinding()
Dim wdApp As Word.Application
Dim wdDoc As Document
Set wdApp = New Word.Application
Set wdDoc = wdApp.Documents.Open(ThisWorkbook.Path & "\Word.docx")
wdApp.Visible = True
Set wdApp = Nothing
Set wdDoc = Nothing
End Sub