I know two couples that got married in the middle part of September, 15/16th ish and they both still did a fall theme wedding. It was funny because they got married a year apart, their weddings were the same weekends (1 year apart), they had the same church, hall, DJ, theme, colors. Both weddings turned out really nice though. I don't remember if they had pumpkins but I know they had corn stalks and indian corn. Your weekend if probably Labor Day weekend, right? The "unofficial" start of fall so I think the fall theme would still work for ya.

I also agree with Tiffany, I think a closer date will make things easier on you for planning. My fiance and I got engaged in February and our date is 7.11.09 and all my friends think that is a long engagement!