I change the start time in 30 minute intervals. I keep the same start time for three weeks. I based my start time decision on the fact that an average foursome takes 2 hours and 20 minutes to play PC, and the sunset calender for Olathe. Shown below is the September Mondays sunset and civil twighlight times for Olathe. One must also consider the possibility for cloudy and overcast skies, that shortens the civil twighligt period considerably.
September 12 Sunset: 7:36pm, Twi: 8:03pm
September 19 Sunset: 7:25pm, Twi: 7:51pm
September 26 Sunset: 7:13pm, Twi: 7:40pm
We could always just keep the start time at 6:00 and finish with GLOW lights. Or, we could start at 5:30 as suggested by the illustriuos Dick and Andy, and have GLOW lights ready in case it did get dim.
Neither will be the case however. Start time for the rest of September is 5:00.