Did you mean 9/2015? 9/16 is 18 months away.
If you apply with more than 6 months remaining on the GC, you will be entitled to free I-151 stamping if your GC expires while your naturalization is still pending.
Having an expired GC at the oath is rarely a problem, but having an expired one at the interview could result in the interviewer insisting that you apply for renewal and get back to them with proof of the renewal application. So if you're past the 6 month cutoff, you'll need to watch and wait and make the decision to apply for renewal based on your interview date.
Also, if you don't already have a Social Security card without the employment restriction wording, and you work for a living, make sure to apply for an unrestricted card before your GC expires. You can use the unrestricted SS card combined with a driver's license or state ID for employment purposes, without having to show the GC.
