Yes, you can begin completing any of the Events in each sequence at any time. Start by tapping on the Event tile in your lobby and finishing any Event on the list. You can complete all of the tasks from one Event before moving on to the next, or you can accomplish a task from an Event and move to the next Event. However, to complete the whole Event challenge, earn the VIP points, and Event completion scratchers, you must complete all the Events before the time expires.