Sounds like we'll be in the World at the same time.

Started the countdown yet?
Really, checking never hurts! Also you're going during a 'slower' time. Read; summer holidays are over. That's a huge plus. At those times flights are booked full a lot more.
I've been keeping an eye out on 'our' flight for a couple of weeks now (I'm a nutcase with these things, I know

), to see what loads are on it these last weeks, esp. on thursday as that's the day we fly. Since last week the flightload has dropped dramatically. From standardly overbooked flights, to flights with seats left over all of the time. Yesterday and today were probably about 50% maybe 60% full.
Not too unto Delta, but play around a bit to see if you can check this. Airlines tend to give this option on their mobile website, if they do hand that info out. It's very likely Delta is blocking an amount of seats at this moment, to offer to their frequent flyers. Most US carriers do so with blocking of 'more desirable' seats. They'll be open to general public at the time of OLCI. Another reason to log onto your reservation at that point, even if you don't do actual OLCI you can stil chance the seats around.