I would recommend showing up 30 minutes prior to departure, this will allow the representative to check you in. Then about 15-20 minutes prior to departure you will walk to where the bus departs from. If you arrive within 15 minutes of departure, look for the bus (if you don't see anyone from the company at the meeting spot). For my trip, once on board we were given entry tickets, audio guide tickets and an itinerary on when the bus is departing each chateau. The driver dropped us off at each chateau and stayed in the same spot until departure; everything worked out great!