To start the story you need to develop one of those situations. What is coming to change your characters' lives. This could be an approaching storm, war, any one of a number of thing. If you choose to begin with this scenario, the one thing to remember is not to start with too large of a coming event. The event and what it will do to your characters is the focus. Another pitfall here is getting involved in the backstory and forgetting what's coming.
Beginning in the middle of the change can be a good place. Here the character knows what has happened and they must decide what to do. Problem here is that the character may become mired in making a decision that he or she has problem deciding what to do. This leads to looking at their every thought and the possible consequences.
Beginning a moment after the change has arrived puts the characters in the midst of reacting to the change. One problem here is they become scattered and their actions become meaningless.
The change might bode disaster or it might not. Good news such as the winning of a lottery, an unexpected inheritance or some other thing can bring a change that will produce problems. Bad enws is a given for propelling the characters into action.
So look at the change. What is the situation. Just what is the change. Who is the focus of the change . What are the consequences.