Bob,
For the first earlybird group its a 7am departure in nice cool air, with a quick blast down 80 with
little to no traffic at this time, then taking scenic route 12 West over to Sonoma in time for Coffee & Pastry in the square. This extends the stay to make more of a day of it - if that's what you prefer. We've started later in the past, and to me it feels like you drive there, stay for a bit, eat lunch, and before you know it you are headed home again, but that works for some too. Sometimes a few will detour on the return trip home past lake-B for a cooler run back or just to extend the day. Whatever floats your boat as they say...
EDIT:
I edited the first and post below to reflect two departure groups at two different times from two different locations for anyone who is interested in riding down with either group caravan.