Until they bring our pick-up time forward an extra five minutes I'm not too stressed about it. If your briefing and checking paperwork (licence, passport, medical blah blah) is done in time for you to be on the bus 75 minutes before departure all well and good. If it isn't, don't get on the bus until you are ready. If you miss some obscure notam about an airway closure in the middle of China saying you had to be on the bus at ETD-75 won't be much of a defense.