Late summer would be good, give us plenty of time to get it scheduled and get ourselves prepared for it. Weekday is when were most likely going to be able to get a day and likely cheaper as well. I would aim for a holiday or something that most people might have the day off anyway like "Labor Day" as they tend to not have those days scheduled and we could possible get it cheaper.
http://www.Nelsonledges.com Their site still has days on weekends available in August and September and not anywhere all the weekdays are full as well. Some kind of BMW club maybe has Sep.19,20,21 scheduled and maybe we could get a day with them or something also. Andy, just let me know if you need help with working with them on scheduling and we can find out what the expected cost will be.