VBA check if object is set

I have a global variable that is an instance of my custom class.

How do I check if the object is set or if I need to initialize it?

If obj Is Nothing Then
    ' need to initialize obj: '
    Set obj = ...
Else
    ' obj already set / initialized. '
End If

Or, if you prefer it the other way around:

If Not obj Is Nothing Then
    ' obj already set / initialized. '
Else
    ' need to initialize obj: '
    Set obj = ...
End If