1- If by creator we mean the power to create, then it is an attribute of essence because it goes back to his power. If we mean the act of creating then it’s an attribute of action.
So the hadith that states that he was the creator even when there was no creation, it means that he had the power to create. Allah doesn’t need to create to earn this title. He has the power to create, whether he chooses to use this power and create or not. Why is the Imam saying this? So no one thinks Allah is in need, and that he needed to create us to earn this title.