Have to agree with Joe. I don't think you'll get much growth. When we built the CFC fields in 2006 we sprigged the fields with "Celebreation" a variety of Bermuda. We did it in early August which was cutting it close. Fortunately the temps held and we got a good growth before the temps dropped. We talked about overseeding but our "expert" discouraged it since the process would introduce unwanted grasses onto the fields (he was a grounds keeper at the local golf club). That was the best advice we could have gotten. We did not play on the fields until the fall of 2007 (let the fields grow for 1 full year). Fortunately our club has a couple of grass experts and we've kept our fields in very good condition. I spent the summer of 2006 building our fields and I'm willing to share any lessons learned. Send me a message if I can be of any assistance.