The big thing I'm still unsure of, though, is how many judges stray from the Federal Law Clerk Hiring Plan (requiring no applications before September). Do you have any idea about this?
Unfortunately, the only way to find out is to narrow down where you'd be willing to go to clerk, and call each and every judge's chambers to ask if they will be hiring for clerks for the year after you graduate, whether they follow the federal plan, and if not, when the judge will be accepting applications.