And what, exactly, would be the point of starting it from outside? Thirty seconds more standing in cooler air perhaps?
If you elect not to strap in at any time when rotors are turning then, in the event of an accident, the Personal Accident insurers will only pay out 50% of the policy limits, as you will have been deemed 50% reponsible for causing your own injuries or demise, same as in your car when it is in motion. Might not bother you, if you have 'croaked', but your family may be a bit peed off about it.