The "kill switch" is mandated switch for motorcycles. It allows the rider to turn the bike off without removing a hand from the grips. Using or not using it does nothing. Not using it does nothing harmful to the bike, does not cause a power surge or anything other than prime the efi system at the same time as energizing the ignition and turning the lights on.
Since all these circuits are on separate breakers, the bike comes alive the way its designed to.
Whether you turn it off first or leave it on makes no more difference than whether you mount or dismount your bike from the right or left side. Its a safety device mandated by the federal government for production motorcycles/scooters/mini bikes/3 wheelers and 4 wheelers.
“When the going gets weird, the weird turn professional....” ~ Hunter S. Thompson~
R.I.P. Rubberdown. 1971-2012