No. Don't worry. You can create an event and then save it for later. We will not publish it without your say so.
Simply click host new event. When you get to the 'create event page' with options for location, date, photo upload etc, you will see in the top right hand corner there is a 'save for later' button. You can click this at any point.
Your event will only be published when you click the 'Make your event live' button, at the bottom of the event preview page.
If you click save for later your event will be sitting in your 'My hosted events' in the draft section.