If you want to browse to a folder by default: For example "D:\Default_Folder" just initialise the "InitialFileName" attribute
Dim diaFolder As FileDialog
' Open the file dialog
Set diaFolder = Application.FileDialog(msoFileDialogFolderPicker)
diaFolder.AllowMultiSelect = False
diaFolder.InitialFileName = "D:\Default_Folder"
diaFolder.Show