[Django]-Is there a way to find in forms .save() method if Model Form is creating a new record or updating existing one?

No, there is no other way to do it. ModelForm has no fields to indicate that object is created or updated. In fact you can pass to ModelForm the unsaved model as the instance and in this case the form will not construct the object at all:

form = MyForm(instance=MyModel())

So checking of the self.instance.pk is the only way for this task.