Attending career fairs

There's no harm in attending a job fair in October. It depends on the hospital. Some hospitals will tell you to apply in Feb/Mar if you are graduating in May; they won't have their new grad jobs posted yet. However, there are other hospitals who recruit new grads in November even though graduation isn't until May or the following July! That happened to two of my colleagues. They went to the job fair in November and did a followup interview in December. When school started back up in January, they received job offers!
You can always make new connections, find out what jobs are out there. So attend in October and you'll know who the recruiters are and when they want new grads to apply. Good luck!